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How  TO  WIRE  BUILDINGS: 


A  MANUAL 
OF  THE  ART  OF  INTERIOR  WIRING. 


BY 


AUGUSTUS     NOLL,    E.E., 

Member  A  m.  Inst,   of  Elec.  Engineers. 

WITH    MANY    ILLUSTRATIONS. 


NEW  YORK  : 

C.   C.   SHKI,I,EY,   PUBLISHER, 
10  &  12  COLLEGE  PLACE. 

1893. 


\ 


Copyright,  1893  : 

CHARLES  C.  SHELLEY, 

New  York. 


SIFT  OF 
ENGINEERING  LIBRARY 


PREFACE. 


It  would  be  impossible  to  exaggerate  the  importance 
of  good  wiring  as  an  element  in  the  prosperity  and 
permanence  of  the  various  electrical  industries  ;  and  the 
writer  of  the  present  modest  volume  believes  that  his 
efforts  to  explain  the  true  principles  of  good  wiring  and 
to  point  out  the  best  methods  will  be  welcomed  cordially 
by  electrical  engineers,  contractors,  wiremen  and  the 
public  generally. 

The  idea  followed  in  inditing  these  pages  has  been  to 
draw  upon  personal  experiences  ranging  over  a  great 
many  years,  and  to  set  forth  in  plain,  simple  language 
the  things  that  must  be  done  and  the  things  that  must 
be  avoided.  Every  part  of  the  subject  is  treated  in  such 
a  manner  that  beginners,  wiremen  and  others  interested  in 
the  practical  branches  of  the  art  of  interior  wiring  can, 
with  a  little  attention,  understand  readily  why  certain 
practices  are  preferable  to  others,  and  how  a  piece  of 
work  can  be  rendered  safe  and  satisfactory.  It  is  believed 
that  practical  advice  from  one  who  has  himself  tested  by 
actual  work  and  observation  the  value  of  every  rule  and 

865697 


IV  PREFACE. 

suggestion  here  offered,  will  be  very  helpful.  While 
much  may  seem  novel,  no  statement  is  made  that  practice 
does  not  confirm,  and  no  method  is  recommended  that 
experience  and  common  sense  do  not  approve. 

There  is  as  far  as  possible  all  avoidance  of  abstruse 
technicalities  in  the  descriptions,  and  the  divisions  have 
been  made  with  a  view  to  an  easier  comprehension  of  the 
different  parts  of  the  subject.  A  special  series  of  draw- 
ings has  been  made  for  the  book  which  will  be  appreciated, 
the  author  thinks,  in  several  quarters  ;  and  many  of  which 
have  long  been  needed. 

It  is  hoped  that  a  perusal  of  this  book  may  lead  many 
workmen  forward  to  the  study  of  other  books  that  they 
have  hitherto  found  too  technical,  so  that  they  will  then 
be  able  to  see  how  close  is  the  relation  between  good  work 
and  sound  theory.  All  that  the  author  asks  credit  for  is 
an  earnest  desire,  of  which  this  little  book  is  the  ex- 
pression, for  the  perfection  of  an  art  to  whose  improvement 
he  has  devoted  all  his  time  and  thought. 

AUGUSTUS   NOLL. 
NEW  YORK  CITY,  June,  1893. 


CONTENTS. 


PAGE 

CHAP.           I.  INTRODUCTION,           ....  3 

"             II.  GENERAL  CONSIDERATIONS,        .         .  5 
"     '      III.  LOCATION  OF  CONDUCTORS,        .         .  8 
"            IV.  DIVISION  OF  CIRCUITS  AND  DISTRI- 
BUTION OF  CURRENT,  ...  15 
"             V.  Loss    OF    ELECTRICAL    ENERGY    IN 

CONDUCTORS,        .         .         .         .24 

VI.  PLANS,       .         .         .         .         .         .  30 

"          VII.  CONDUIT  WIRING,     .         .         .         .  33 

"        VIII.  SWITCHBOARDS,           ....  49 

"            IX.  APPLIANCES  AND  CONNECTIONS,         .  51 

"             X.  CONVERTER  WORK,            ...  53 

"            XL  OVERHEAD  WIRING,           ...  63 

XII.  FUSE  WIRE,       ....  66 

XIII.  INSULATION,       ....  70 

XIV.  ELECTROLYSIS,  ....  76 
"          XV.  ADVERSE  WIRING  CONDITIONS,          .  80 

XVI.  THEATRE  AND  STAGE  LIGHTING,        .  85 

"       XVII.  PLANS  OF  DISTRIBUTION,            .         .  95 

"     XVIII.  DISTRIBUTION  OF  LIGHT,            .         .  113 


VI  CONTENTS. 

PAGE 

CHAP.     XIX.     DISTRIBUTION  OF  LABOR  AND  HINTS 

TO  FOREMEN,        .         .         .         .       121 
XX.     PRELIMINARY  TO  RULES,  ELECTRICAL 

DATA,  ETC.,  .         .         .         .125 

XXI.     RULES  FOR  ASCERTAINING  REQUIRED 

SIZES  OF  WIRE,  .  ,  .  .135 
"  XXII.  ENERGY — POWER,  ....  140 
"  XXIII.  DYNAMOS  AND  MOTORS,  .  .  .143 

«     XXIV.     PULLEYS, 150 

"      XXV.     BELTING, 153 

"     XXVI.     ENGINES, 155 

"  XXVII.     CONCLUSION,  158 


HOW  TO  WIRE  BUILDINGS. 


CHAPTER  I.       ,>,   .  t_J 

INTRODUCTION. 

1.  In  the  science  of  electricity  the  question  of 
"wiring"  is  hardly  considered,  but  in  the  appli- 
cation of  electricity  from  a  practical  and  commer- 
cial standpoint  it  is  one  of  the  most  important  and 
difficult  factors.  It  embraces  nearly  every  branch 
of  what  is  termed  "  construction  work."  The 
student  in  electricity  may  have  sufficiently  mas- 
tered the  theory  of  electrical  currents,  together  with 
a  knowledge  of  the  different  definitions  and  terms, 
to  an  extent  that  will  enable  him  to  " lay-out" 
wiring,  on  paper,  in  the  form  of  a  plan,  showing 
the  different  circuits,  sizes  of  wires,  etc. ;  and  while 
his  work  may  be  all  that  is  desired  in  the  shape  of 
a  plan,  it  will  very  often,  even  while  the  wires  are 
being  installed,  fail  of  its  purpose,  owing  to  the 
conditions  which  exist  in  the  building  and  which, 
were  not  considered  or  known  at  the  time  of  making 
the  plan.  The  mere  electrical  student  cannot  thor- 


4  HOW   TO    WIRE   BUILDINGS. 

oughly  understand  the  ' '  art  of  wiring, ' '  because  its 
essential  features  are  purely  practical,  and  can  only 
be  acquired  by  experience  and  strict  observation. 

2.  On  the  other  hand,  the  practical  wireman  or 
beginner  4wi}l  make  more  rapid  advancement  if  he 
wilWbkilne*  his  studies  to  a  general  knowledge  of 

f  ble^ticit^^sufficient  to  enable  him  to  trace  the 
directioV  of  the  current  in  dynamos,  motors  and 
appurtenances,  and  also  in  the  wires,  rather  than 
fill  his  mind  with  all  the  different  theories  re- 
garding magnetism  and  electricity,  which  will 
only  tend  to  confuse  him  and  make  the  different 
methods  and  systems  of  wiring  appear  more  diffi- 
cult and  complex.  When  once  the  practical  branch 
of  wiring  is  sufficiently  mastered,  then  will  he  be 
enabled  to  understand  theory  more  easily,  and  he 
can  gradually  acquire  a  knowledge  of  the  various 
terms,  and  of  their  relation  to  each  other. 

3.  I  have  in  these  pages  endeavored  to  explain, 
and  illustrate,  the  more  important  features  con- 
tinually  encountered    in  practical  wiring,   in    as 
simple  a  manner  as  possible,  eliminating  all  tech- 
nicalities, so  that  this  book  may  prove  of  interest, 
not  only  to  the  student,  but  also  to  the  workman, 

In  the  "art  of  wiring"  as  practically  applied  in 
electric  lighting  and  kindred  purposes. 


HOW   TO   WIRE   BUILDINGS. 


CHAPTER  II. 


GENERAL  CONSIDERATIONS. 

4.  Electrical  ' '  construction  work ' '    covers  such 
a  vast  field,  that,  not  to  make  the  work  too  lengthy, 
nor  to  exceed  our  proper  limits,  we  will  only  treat 
of  that  portion  which  relates  to  the  " wiring"  of 
buildings,    and    such    other    branches    incidental 
thereto,  for  electric  lighting.     It  is,  in  this  branch 
of  the  work,  that  the  conditions  are  not  fixed,  and 
that  those  having  charge  of  the  work  must  depend 
largely   on  their   own   knowledge,  judgment  and 
ingenuity.     There  may  be,  for  example,  a  change 
in  the  location   or  number  of  lamps  ;  change  in 
location   of  dynamo  (in  the   case   of    an  isolated 
plant),  and  numerous  other  changes  which  are  liable 
to  occur,  and   for  which   no  provision   had  been 
made,  when  the  work  was  originally  "laid  out." 

5.  Ordinarily,  the  foreman  in  charge  should  be 
competent :  To  draw  a  plan  of  each  floor  to  be 
lighted ;   to    understand    and    familiarize  himself 
with  the  physical  and  other  conditions,  and  from 
this  data,  proceed  (leaving  nothing  to  chance)  to 
complete  the  plan  of  the  wiring  work  and  locate 


•6  HOW   TO    WIRE   BUILDINGS. 

the  cut-outs  and  switches;  locate  the  wires,  and 
decide  on  the  method  of  distribution,  and  locate 
the  feeding  points  between  the  Feeders,  Mains, 
and  Lamp  Circuits;  to  decide  on  the  most  satis- 
factory percentage  of  loss  of  energy  to  be  allowed 
in  the  different  portions  of  the  wiring  system,  so 
that  the  Difference  of  Potential,  or  pressure  at  the 
lamps,  will  practically  be  equal  throughout  the 
building. 

6.  The  foreman  must  also  be  able  to   compute, 
.according  to  the  per  cent,  of  loss,  the  cross-section 
or  size  of  wire  necessary  for  use  in  the  different 
parts  of  the  wiring  system ;  to  determine  the  most 
satisfactory  kind  and  length  of  fixture,  and,  when 
the  wiring  work  is  completed;  to  set  up  and  run 
(in  the  case  of  an  isolated  plant)  the  dynamo,  and 
connect  same,  with  the  wiring  and  the  instruments 
usually  provided;  to   compute  the  width  of  belt 
necessary  and  also  the  diameter  and  face  of  driving 
pulley  if  belted  to  a  pulley  on  shafting,   and  in 
case  of   necessity  run  an  engine ;   and,  finally,  to 
locate  and  repair  all  defects  in  the  wiring,    and 
also  slight  defects  in  the  dynamo,  etc. 

7.  These  items  form  the  necessary  qualifications 
to  ensure  satisfactory  and  lasting  results.     The  suc- 
cessful operation  of  the  plant  depends,  to  the  great- 
est extent,  on  the  manner  in  which  the  wiring  was 


HOW   TO   WIRE   BUILDINGS.  7 

"laid  out,"  and  electric  lighting  companies  can 
trace  the  greatest  part  of  the  dissatisfaction  on  the 
part  of  their  customers  to  the  defective  manner  in 
which  the  wiring  work  was  installed. 


8  HOW   TO   WIRE   BUILDINGS. 


CHAPTER  III. 


LOCATION  OF  CONDUCTORS. 

8.  It  is  sometimes  the  case  in  installing  wires  in 
buildings  that,  although  the  best  grade  of  materi- 
als, of  the  several  kinds  usually  employed  for  the 
work,  was  used,  the  results  have  been  unsatisfac- 
tory ;  the  workmanship  and  appearance  may  have 
been  all  that  could  be  desired,  and  yet  in  a  short 
time  after  the  current  has  been  in  use  the  work 
breaks  down,  and  short  circuits,  grounds,  leaks, 
etc.,  are  of  common  occurrence.     The  fault  is  usu- 
ally due  to  the  location  of  the  wires. 

9.  The  following  adverse  conditions  should  be 
avoided  as  much  as  possible,  and  where  it  is  im- 
possible to  do  so,  proper  safeguards,  according  to 
the  condition,  must  be  provided :  Excessive  moist- 
ure, atmospheric  changes,   extreme  variations   of 
temperature,  extremely  high  temperature,   gases, 
acids,  lye,  lime,  cement,  etc.,  and  last,  but  one  of 
the  most  important  conditions,  mechanical  inter- 
ference. 

10.  In  dealing  with  the  first  class  of  conditions 
the  best  plan,    of  course,    is  to  shun  dangerous 


HOW   TO   WIRE   BUILDINGS.  9 

places,  but  the  location  of  the  lamps  may  make  it 
impossible.  Generally,  the  best  grade  of  materials 
and  superior  workmanship  will  lessen  the  chances 
of  trouble,  and  with  the  high  grade  materials,  as 
now  manufactured,  very  little  trouble  should  be 
experienced. 

11.  By  the  use  of  conduits  (see  chapter  on  con- 
duits) and  high  grade  moisture-proof  wire,  pro- 
viding a  separate  conduit  for  each  wire,  the  results 
have  been  most  satisfactory.     Special  care  should 
be  taken  to  have  the  joints,  on  both  the  wire  and 
conduits,   water-tight,  and  equally  as  well   insu- 
lated as  the  remainder  of  the  wire  and  tube  form- 
ing the  circuit.     The  cut-outs  and  switches  should 
be  grouped  and  located  in  places  free  from  the 
deleterious  conditions  above  noted. 

12.  The  lamps,   sockets  and  fixtures  should  be 
designed  with  a  view  to  protecting  the  electrical 
connections   contained    therein.      Keyless   sockets 
should  be  used,  and  the  lamps  should  be  controlled 
by  switches.     The  lamp  should  be  provided  with 
an  extra  safeguard,  arranged  to  exclude  moisture 
and  gas.     The  design  of  these  is  generally  similar 
to  that  of  a  fruit  jar,  or  bulb  of  thick  glass  her- 
metically sealed  by  means  of  rubber  bushings  and 
metallic  cover.     If  the  style  of  work  is  what  is 


10  HOW   TO   WIRE   BUILDINGS. 

known  as  "open"  or  "exposed"  work,  the  use 
of  conduits,  in  many  cases,  will  be  unnecessary, 
but  care  must  be  taken  to  keep  the  conductors  free 
from  contact  with  the  building,  which  can  usually 
be  accomplished  by  the  use  of  suitable  insulators. 

13.  In  dealing  with  conditions  that  come  under 
the  head  of  mechanical  interference,  care  must  be 
taken  to  locate  the   conductors  and  all  appurte- 
nances used  in  the  wiring  work  in  such  places  that 
while  they  are  of  easy  access  to  persons  in  charge, 
they  are    still    inaccessible    to  inquisitive,    unin- 
formed and  malicious  persons. 

14.  When  installing  wires  in  a  building  in  the 
course  of  erection,  be  careful  to  isolate  and  prevent 
contact  with  the  work  of  other  mechanics  as  much 
as  possible.     As  the  building  is  in  a  rough  state, 
the  wires  must  be  handled  with  care  to  prevent 
abrasions  in  the    insulation.     The  nature  of  the 
material  forming  the    insulation    will  not  admit 
of  rough  treatment,   such  as  dragging  along  the 
rough  floors,  or  across  piles  of  brick  and  mortar, 
etc.     In  short,  the  wires  should  be  so  treated  that 
the  insulation  covering  them  will  not  be  bruised, 
cut  or  perforated  in  the  slightest  degree.     In  an 
otherwise  perfect  insulation  the  most  minute  dis- 
arrangement of  its  parts  will  often  impair  its  use- 


HOW   TO    WIRE   BUILDINGS.  11 

fulness  and  permanence,  and  while,  in  some  cases, 
the  defect  will  at  once  become  evident,  still,  in 
other  instances,  the  fault  may  not  appear  until 
after  the  work  has  been  in  use  for  some  time,  when 
remedying  the  defect  will  cause  expense  and  ex- 
treme annoyance,  and  will  necessitate  the  cutting 
of  the  plaster  on  the  side  walls  or  ceilings. 

15.  The  destruction  of  the  insulation,  due  either 
to  natural  deterioration,  or  other  causes,  is  the 
greatest  source  of  trouble  in  electric  lighting  (see 
chapter  on  electrolysis).     Hence  the  use  of  inferior 
insulated  wires  is  always  false  economy. 

16.  Keep  the  work  clear  of  and  at  some  dis- 
tance from  places  where  exposed  wood-work  is  to 
be  fastened,  such  as  the  trim  of  doors,  windows, 
chair-rails,  picture  mouldings,  base-boards,  etc.,  as 
these  places  will  be  plastered,  and  should  the  wires 
or  conduits  be  located  at  these  particular  points, 
their  liability  to  being  cut  by  nails  is  very  probable. 

17.  When  wires  are  placed  under  the  floors  or 
between  partitions,  they  should  be  separated  from 
each  other  and  fastened  beyond  the  reach  of  the 
floor  nails   or  lath  nails.     Inaccessibility  of  the 
conductors  should  be  avoided  as  much  as  possible, 
and  concealment  of  same  should  only  be  resorted 
to  where  definite  channels,  such  as  conduits,  have 


12  HOW   TO   WrRE   BUILDINGS. 

been  provided.  Do  not  sacrifice  necessary  safe- 
guards for  a  neat  appearance,  and  do  not  "fish" 
electric  light  conductors,  in  the  same  manner  as 
burglar  alarm,  annunciator,  electric  bell  and  such 
like  conductors  usually  are.  In  the  latter  cases 
the  wires  are  "fished"  or  threaded  here,  there  and 
everywhere,  so  that  they  may  be  hidden  from 
sight,  but  in  the  case  of  lighting  circuits,  no  con- 
ductors should  be  inserted  in  a  channel  unless  the 
exact  condition  of  same  is  known.  In  this  case 
you  are  dealing  with  Jiorse-power,  and  nothing 
must  be  left  to  chance.  Wires  installed  in  build- 
ings must  not  be  treated  according  to  the  apparent 
conditions.  In  every  case  a  personal  inspection  by 
one  experienced  in  this  branch  of  the  work  is  the 
only  safe  method. 

18.  Marble  and  tiled  floors,  etc.,  should  be 
avoided  as  a  place  to  locate  wires  whether  con- 
duits are  used  or  not.  In  cleaning  such  floors,  sul- 
phuric acid  is  made  use  of;  and  materials  of  this 
nature  absorb  moisture,  which  will,  in  addition  to 
the  action  of  the  acid,  create  another  source  of 
trouble.  Regarding  moisture  and  like  conditions, 
no  building  for  electric  lighting  purposes  can  be 
assumed  to  be  dry.  While  it  may  have  been  dry 
at  the  time  of  installing  the  wires,  the  probability 
of  this  condition  being  changed  is  so  great  that  as 


HOW   TO   WIRE  BUILDINGS.  13 

a  safe  rule  it  should  be  treated  as  damp  and  the 
corresponding  grade  of  material  used  as  though  it 
were  continually  damp  or  wet,  because  the  water- 
pipes  may  leak  or  burst,  or  the  bath-tub  or  basins 
may  overflow. 

19.  When  wires  are  encased  in  wood  mouldings, 
the  latter  should  consist  of  a  grooved  back  board 
and  a  tight  fitting  cover,  and  in  stores  and  similar 
places  the  ceilings  should  be  kept  clear  of   same 
as  much  as  possible.     A  separate  groove  should  be 
provided  for  each  wire,  and  in  no  case  should  wires 
of  the  same  or  different  polarity,  forming  different 
circuits,  be  placed  in  the  same  groove.     That  style 
of  wiring  should  never  be  made  use  of  in  places 
where  adverse  conditions  exist. 

20.  In  hotels,   office  buildings,  residences,   etc., 
locate  all  the  appliances,  main  and  feeding  lines, 
in  hallways  or  closets,  so  as  not  to  have  to  enter 
rooms.     The  annoyance  of  interference,  both  to  the 
inmates  and  workmen,  may  thus  be  obviated  while 
the  work  is  being  installed.     It  will  also  obviate 
annoyance  in  the  future,  when  repairs,  renewals  or 
alterations  may  be  necessary.     In  workshops,  fac- 
tories, etc.,  the  wires  are  usually  held  to  the  ceil- 
ing by  means  of  cleats,   or  fastened  to  porcelain 
knobs.     The  wires   should   always  be   located  in 


* 

14  HOW   TO   WIRE   BUILDINGS. 

such  places  on  the  ceiling  as  are  clear  of  shafting, 
belts,  etc.,  and  where  the  work  can  proceed  with- 
out interruption  either  to  the  wiremen  or  the  hands 
and  machinery  employed  on  the  premises. 


HOW   TO   WIRE   BUILDINGS.  15 


CHAPTER  IV. 

DIVISION  OF  CIRCUITS  AND  DISTRIBUTION  OF  CUR- 
RENT. 

21 .  When  the  building  has  been  inspected  and 
the  various  conditions  in  the  different  parts  have 
been  noted,  the  question  of  distributing  the  cur- 
rent then  demands  attention.  The  most  impor- 
tant considerations  are  the  equalization  of  pressure 
throughout  the  different  lamp  circuits,  and  to  di- 
vide the  circuits  according  to  the  manner  in  which 
the  lamps  will  be  used.  In  a  building  where  the 
wires  are  to  be  concealed  (new  structure)  the  best 
mode  of  procedure  is  to  locate  the  various  closets 
or  boxes  for  the  reception  of  the  cut-outs  and 
switches.  The  location  is  governed  by  the  number 
of  lights,  and  size  and  shape  of  the  building.  Gen- 
erally from  four  to  eight  lamp  circuits  are  carried  to 
each  box.  The  box  should  be,  as  nearly  as  possi- 
ble, in  the  centre  of  the  space,  the  lamps  in  which 
are  supplied  with  current  by  the  circuits  center- 
ing at  this  box.  After  locating  the  box  and  divid- 
ing the  lights  into  circuits,  the  next  step  is  to  de- 
cide upon  the  method  of  dividing  and  connecting 


16  HOW   TO    WIRE   BUILDINGS. 

the  main  and  feeder  wires.  The  number  of  mains 
and  feeders  depends  upon  the  size  of  the  building 
and  number  of  lights.  Locating  the  connecting 
points  between  the  mains  and  feeders  depends  upon 
the  location  and  number  of  lights  at  each  box  or 
ramifying  point,  the  distance  between  the  various 
feeding  points  and  the  use  of  the  lights.  That  is 
to  say,  in  one  part  of  the  structure  the  lamps  may 
be  used  continuously,  and  in  another  part  only  a 
few  out  of  a  great  many  may  be  used  at  any  one 
time.  The  building  should  be  cut  up  or  divided 
into  sections.  Either  each  floor  or  each  side  of  the 
building  should  comprise  a  separate  circuit,  accord- 
ing to  the  size  of  the  building  (see  chapter  on  ex- 
planation of  distribution).  If  divided  perpendic- 
ularly, one  or  more  mains  feeders  are  provided,  ex- 
tending from  the  main  switchboard  in  the  dynamo- 
room  to  the  central  point  between  the  feeding  or 
connecting  points  on  the  line  of  the  mains.  The 
mains  are  usually  run  from  the  top  to  the  lowest 
floor,  and  at  each  floor  connections  are  made  to 
wires  which  carry  the  current  to  the  different  lamp 
circuits.  These  floor  mains  connect  to  one  or  two 
cut-out  boxes.  If  they  are  located  somewhat  closely 
together,  then  only  one  set  of  main  wires  are  re- 
quired; but  should  the  distance  between  them  be 
great,  the  floor  main  must  extend  to  a  point  mid- 


HOW   TO   WIRE   BUILDINGS.  17 

way  between  them,  and  again  be  divided,  so  that  a 
branch  from  each  will  connect  with  the  lamp  cir- 
cuit independent  of  the  other. 

Should  the  structure  be  composed  of  numerous 
floors,  it  will  be  the  best  plan,  instead  of  connect- 
ing the  main  feeder  from  the  dynamo-room  to  the 
mains  in  the  central  point,  to  provide  a  set  of  sub- 
feeders  starting  and  connecting  with  the  main 
feeders  at  its  terminals,  which  should  extend  both 
ways  and  connect  with  the  vertical  mains  at  a 
point  about  one-quarter  of  the  whole  distance  from 
the  end.  The  idea  of  feeding  in  this  manner  is  to 
equalize  the  lighting ;  that  is,  to  balance  the  elec- 
trical pressure  and  the  number  of  lamps  in  use,  so 
that  the  variations  constantly  occurring  will  not 
affect  the  pressure  to  an  extent  where  the  life  of 
the  lamps  will  be  shortened. 

22.  The  various  systems  of  feeding  all  tend  to 
this,  as  is  shown  in  the  plans  (see  chapter  on  same). 
From  these  it  will  be  seen  that  the  circuits  are  con- 
stantly being  divided  into  smaller  sections,  so  that 
the  electrical  pressure  is  practically  the  same 
throughout,  and  that  each  branch  is,  to  a  certain 
extent  (electrically),  independent  of  the  others. 

When  ''laying  out"  the  feeding  lines,  not  only 
should  the  work  be  done  with  a  view  to  equalizing 
the  pressure  on  the  wire  with  the  full  load  on,  but 


18  HOW   TO    WIRE   BUILDINGS. 

also  for  periods  when  only  a  few  lamps  are  in  use 
on  any  one  branch,  while  in  still  another  all  the 
lamps  were  in  use,  so  that  the  variation  of  pressure 
on  the  conductors  connecting  with  the  few  lights 
will  be  'reduced  to  a  minimum.  To  accomplish 
this,  it  is  at  times  necessary  to  install  two  or  more 
sets  of  feeders,  connected  at  the  same  main  con- 
ductors, but  at  different  locations.  Again,  in  other 
instances,  such  as  a  large  isolated  plant,  or  where 
the  lighting  covers  a  large  area,  it  is  necessary,  in 
order  to  equalize  the  electrical  pressure  at  the 
lamps,  to  provide  and  connect  in  the  main  feeder 
circuits  regulating  devices  for  controlling  the  pres- 
sure. 

23.  In  a  plant  where  the  loss  of  electrical  energy 
in  the  conductors  has  been  computed  at  a  high 
rate,  the  pressure  at  the  lamp  will  be  at  the  rated 
amount  only  when  all  the  lamps  are  in  use;  and, 
should  only  one-half  be  in  use  on  any  one  section, 
the  percentage  of  loss  in  that  section  will  be  only 
one-half  of  that  in  which  all  the  lamps  are  in  use. 
Consequently,  the  j>ressure  on  the  wires  in  the  sec- 
tion where  only  one-half  are  used  will  be  greater 
than  that  at  which  it  was  rated,  and  the  result 
would  be  excessive  breakage  of  lamps. 

To  overcome  this  defect  is  the  function  of  the 
pressure  equalizer.  It  may  not  be  amiss  to  here 


HOW   TO   WIRE   BUILDINGS.  19 

explain  what  work  the  equalizer  performs  and  the 
difference  between  it  and  a  pressure  regulator. 

24.  A  PRESSURE  REGULATOR  generally  consists  of 
a  coil  or  numerous  coils  connected  in  the  field  or 
magnetic  circuit  and  is  usually  (at  the  present 
time)  controlled  automatically,  although  regulat- 
ing instruments  are  constructed  which  can  be  gov- 
erned by  hand.  The  coils  are  placed  directly  in 
the  magnets,  as  in  a  compound  wound  machine,  or 
by  the  use  of  magnets,  all  or  any  part  of  the  coils 
can  be  thrown  in  or  out  of  the  field  circuit.  As  the 
lamps  are  connected  or  disconnected  on  the  various 
circuits,  so  will  the  strength  of  the  pressure  in- 
crease or  decrease.  As  the  pressure  increases,  the 
coil  or  coils  are  thrown  in  circuit,  and,  according 
to  their  resistance,  the  pressure  is  decreased  until 
it  is  at  its  normal  strength.  The  pressure  is  kept 
at  a  constant  strength  at  the  dynamo  brushes. 

Should  there  be  two  or  more  independent  sets  of 
feeders  carrying  current  to  different  parts  of  the 
structure,  and  on  one  set  all  the  lamps  be  in  use, 
the  pressure  at  the  lamps  in  this  section  would  be 
normal;  but  if  on  another  only  a  few  out  of  a 
large  number  of  lamps  were  in  use,  the  pressure 
would  be  greater  than  that  at  which  it  was  rated. 
The  pressure  required  for  the  lamps,  plus  the  per- 
centage of  loss  in  the  conductors  (assuming  no  loss 


20  HOW   TO    WIRE   BUILDINGS. 

on  the  line  with  only  a  few  lamps  in  use),  would 
equal  the  pressure  at  ihese  particular  lamps,  and  if 
the  percentage  of  loss  was  computed  at  10  per 
cent.,  then  this  amount  would  represent  the  in- 
creased pressure.  To  overcome  this  and  equalize 
the  pressure  on  this  particular  line  without  affect- 
ing the  pressure  on  the  other  circuits,  the  EQUAL- 
IZER is  used.  It  consists  of  a  coil  or  numerous 
coils,  divided  in  sections  and  connected  to  plates 
fastened  to  a  slab  of  slate  known  as  the  equalizer 
face  board.  The  coils  are  thrown  in  or  out  of  the 
feeder  circuit  by  means  of  a  movable  connecting 
plate  fastened  to  a  handle.  In  the  case  of  a  pres- 
sure regulator,  the  diameter  of  the  wires  is  small, 
as  they  only  carry  the  amount  of  current  carried 
by  the  magnet  wires,  but  the  equalizer  being  con- 
nected directly  in  the  circuit,  it  must  have  sufficient 
carrying  capacity  to  carry  the  full  amount  of  the 
current  necessary,  according  to  the  number  of 
lamps  on  the  circuit,  without  heating.  The  size 
and  length  of  the  wire  forming  the  coils  depend 
upon  the  number  of  lamps  and  the  percentage  of 
loss  allowed  in  the  conductor.  Where  several  sets 
of  feeders  are  used,  each  set  should  be  provided 
with  an  equalizer.  The  equalizer  is  connected  on 
one  side  of  the  circuit  only,  in  a  similar  manner  to 
a  one-pole  switch.  Throwing  the  coils  in  or  out  of 


HOW   TO    AVIRE   BUILDINGS.  21 

the  circuit  is  governed  by  the  indications,  as  shown 
on  the  scale  of  the  pressure  indicators,  which  are 
provided  and  set  in  a  place  near  the  equalizer  face 
board.  The  indicator  is  connected  in  the  circuit 
by  a  set  of  pressure  wires  which  connect  with  the 
circuit  at  the  center  of  distribution,  and  as  the 
pressure  varies  at  that  point,  the  amount  of  varia- 
tion will  be  indicated  by  the  needle  as  it  travels 
across  the  scale  of  the  indicator,  so  that  should  the 
instrument  indicate  excessive  pressure  at  the  cen- 
ter of  distribution,  the  current  can  be  brought  to 
normal  strength  by  connecting  or  throwing  in  the 
circuit  sufficient  coils,  the  combined  resistance  of 
which  will  decrease  the  pressure  to  an  extent  where 
it  will  be  equal  to  that  required  by  the  lamps  to 
keep  them  up  to  their  rated  candle-power. 

25.  To  return  to  the  subject  of  distribution  again. 
The  number  of  circuits  should  be  as  many  as  prac- 
ticable ;  the  greater  the  number,  the  less  the  vari- 
ation that  can  ensue. 

The  system,  as  explained,  is  known  as  the 
" panel"  or  " grouping"  system,  and  is  princi- 
pally used  in  new  structures,  office  buildings, 
hotels  and  such  structures.  In  factories,  stores, 
etc.,  the  method  of  distributing  the  current  in 
the  main  add  feeders  is  the  same,  but  the  lamp 
circuit  wires,  instead  of  being  grouped,  are  con- 


22  HOW   TO   WIRE   BUILDINGS. 

nected  at  the  nearest  point  with  a  ceiling  or  floor 
main  which  extends  through  the  whole  length  of 
the  building.  The  lamp  circuits  terminate  in  a 
cut-out  which  is  connected  to  the  mains.  The 
wires  are  either  exposed  or  covered  by  grooved 
wood  mouldings.  In  all  structures  where  the  con- 
ditions are  such  that  all  the  lamps  on  certain  cir- 
cuits are  used  at  a  given  time,  it  is  preferable  to 
connect  them  to  a  special,  independent  feeder,  so 
that  the  pressure  on  the  circuits  connected  to  the 
lamps  used  at  intervals  can  be  more  nicely  regu- 
lated. 

The  lamps  that  are  usually  turned  on  and  off  at 
stated  times,  or  which  are  only  used  on  special 
occasions,  are  generally  the  entrances,  hall,  stair- 
ways, reading  and  waiting  rooms,  etc. 

26.  In  all  wiring  installations  the  public  lights 
should  form  a  separate  circuit. 

The  public  lights  are  generally  those  in  public 
parts  of  the  building,  and  also  generally  include 
the  engine-room,  cellar,  etc. 

All  residences,  hospitals,  etc.,  should  be  pro- 
vided with  a  night  circuit,  having  one  or  more 
lights  in  the  hallway  on  each  floor,  and  connected 
in  such  a  manner  that  they  can  be  connected  or 
disconnected  from  one  or  more  places,  ^and  can  also 
be  connected  to  the  burglar  alarm  and  light  auto- 


HOAV   TO   WIRE  BUILDINGS.  23 

matically  in  a  time  of  danger.  This  circuit  is  a 
great  accommodation  in  case  of  sickness,  sudden 
alarm,  etc. 


24:  HOW   TO   WIRE   BUILDINGS. 


CHAPTER  Y. 

Loss  OF  ELECTRICAL  ENERGY  IN  CONDUCTORS. 

27.  The  expression  "percentage  of  loss,"  when 
used  in  connection  with  electric  lighting,  signifies 
the  amount  of  electrical  energy  expended  in  the 
conductors  and  is  due  to  their  resistance.  The 
rate  is  governed  by  the  local  conditions,  but,  usu- 
ally, wiring  connected  to  mains  from  central  sta- 
tions is  figured  on  a  basis  of  two  per  cent,  loss,  and 
wiring  for  isolated  plants  at  five  per  cent.  loss. 
To  a  certain  extent,  it  is  governed  by  financial  con- 
ditions, that  is,  the  percentage  of  loss  is  increased 
in  cases  where  fuel  is  cheap  or  when  water-power 
is  used.  As  a  general  rule  for  ordinary  isolated 
plants  it  may  be  stated  thus :  Decrease  the  loss 
and  the  cost  of  maintenance  is  lessened,  but  de- 
crease the  percentage  of  loss  and  the  first  cost  is 
increased.  It  is  preferable  to  slightly  increase  the 
first  cost  by  wiring  at  a  low  rate  of  loss  because  the 
decreased  cost  of  maintenance  will  more  than  offset 
the  difference  in  first  cost  in  generating  the  cur- 
rent by  the  saving  in  fuel.  The  liability  to  exces- 


HOW   TO   WIRE  BUILDINGS.  2i) 

sive  lamp  breakage  is  also  obviated  when  the  per- 
centage of  loss  in  the  conductor  is  low. 

28.  The  first  cost,  assuming  the  boiler,  engine, 
etc.,  to  be  already  installed,  consists  of  the  gener- 
ating apparatus  and  its  appurtenances,  wire,  ap- 
pliances, fixtures,  lamps  and  cost  of  labor  for 
installing  same.  With  proper  care,  the  generating 
apparatus,  its  appurtenances,  wire  appliances  and 
fixtures,  will  not  depreciate  to  any  considerable 
extent.  Therefore,  the  cost  of  maintenance  con- 
sists chiefly  in  the  amount  of  fuel  necessary  for 
generating  current  and  the  renewal  of  lamps. 
The  first  item  is  governed  by  the  amount  of  cur- 
rent required  to  maintain  the  rated  candle-power  in 
each  lamp.  (See  formula  electrical  energy.) 

The  renewal  of  lamps  depends  largely  on  the 
breakage  due  to  the  action  of  excessive  current. 
When  the  pressure  is  normal,  the  action  of  the 
current  in  passing  through  the  carbon  is  such  that 
the  carbon  is  gradually  decomposed  and  disrupted 
to  an  extent  that  finally  the  carbon  breaks.  Under 
ordinary  normal  conditions  the  lamp  will  give  con- 
tinual service  for  from  600  to  1,500  hours.  This  is 
termed  "the  life  of  the  lamp,"  but  should  the  elec- 
trical pressure  vary  so  that  at  certain  times  it  is 
greater  than  the  strength  required,  the  carbon  will 


26  HOW  TO   WIRE  BUILDINGS. 

be  overtaxed ;  the  strain  will  be  too  great,  the  dis- 
ruptive action  will  be  increased  and  the  carbon  will 
become  defective  and  weak,  and  usually  in  a  short 
time  it  will  break.  The  amount  of  coal  consumed 
is  governed  by  the  amount  of  electrical  energy 
generated  in  the  dynamo,  and  if  ten  per  cent,  of 
the  electrical  energy  is  required  to  overcome  the 
resistance  in  the  conductors,  then  practically  ten 
per  cent,  of  the  total  amount  of  fuel  used  is  the 
cost  of  carrying  the  current  from  the  dynamo  to 
the  lamps.  From  this  it  will  easily  be  seen  that 
the  question  of  percentage  of  loss  in  the  conductors 
must  be  most  carefully  considered,  not  only  from 
an  electrical  but  also  from  a  commercial  stand- 
point. Another  important  consideration  is  to  have 
the  percentage  of  loss  distributed  properly  in  the 
different  conductors  forming  the  circuit.  The  most 
general  and  satisfactory  method  is,  assuming  the 
loss  to  be  five  per  cent.,  to  allow  one-half  per  cent, 
in  the  lamp  circuit,  one  per  cent,  in  the  floor 
mains,  one  and  one-half  per  cent,  in  the  vertical 
mains  and  two  per  cent,  in  the  main  feeders. 

While  the  term  "percentage  of  loss"  indicates  a 
loss  of  energy  between  the  dynamo  and  lamps, 
commercially  it  is  considered  as  the  cost  of  trans- 
mission, and,  if  intelligently  considered,  will  not 
be  treated  as  a  waste  of  power,  but  as  a  legitimate 


HOW   TO   WIRE   BUILDINGS.  27 

item  in  the  cost  of  lighting.     No  energy  can  be 
transferred  without  loss  or  cost. 

29.  To  demonstrate  the  principle  more  clearly, 
assume  a  lamp  located  at  a  distance  of  1,000  feet 
from  the  dynamo.  The  resistance  of  the  lamp  (the 
resistance  of  lamp  is  always  figured  at  the  time  the 
lamp  is  hot,  or  at  incandescence)  is  90  ohms,  and 
it  requires,  to  bring  same  to  its  rated  candle-power, 
a  current  of  one-half  ampere  at  45  volts.  We  will 
decide  to  lose  ten  per  cent,  of  the  electrical  energy 
in  the  transmission  of  the  current  from  the  dy- 
namo to  the  lamp,  in  the  conductors.  If  the  differ- 
ence of  potential  at  the  brushes  of  the  dynamo  =  45 
volts,  the  difference  of  potential  at  the  lamp  would 
equal  45  volts — ten  per  cent,  loss  =  41.5  volts.  But 
we  wish  to  get  a  pressure  of  45  volts  at  the  lamp, 
which  is  necessary  to  bring  the  lamp  to  its  rated 
candle-power.  Therefore,  45  volts  only  represent 
90  per  cent,  of  the  pressure.  Thus  50  volts  =  the 
pressure  at  the  dynamo  brushes.  This  lamp  hav- 
ing a  resistance  of  90  ohms;  2,000  feet  of  wire 
being  required  to  connect  same  with  the  dy- 
namo ;  ten  per  cent,  being  the  loss  expended  in 
the  conductors,  and  90  ohms  representing  90  per 
cent,  of  the  total  resistance  of  the  circuit,  the  2,000 
feet  of  wire  must  equal,  in  resistance,  ten  per  cent. 


28  HOW   TO   WIRE   BUILDINGS. 

of  the  entire  circuit,  which  is  10  ohms.  Now,  to 
find  the  electrical  energy  expended  in  the  conduct- 
ors and  lamp  expressed  in  watts  (see  formula)  : 

=  C=  /2  and  C  X  E=  watts  =  ^  x  45  =*  22^ 


R  =  90 

watts  expended  in  lamp,  and  }4  X  5  =  2y£  watts 
expended  in  conductor.     Or,  C'2  x  .R  =  watts. 

Therefore, 

.5  X  .5  x  90  =  22.5  watts  expended  in  lamp,  and 
.5  X  .5  X  10  =    2.5      "  "  "  conductor. 

In  both  of  the  preceding  instances  it  was  shown 
that  the  lamp  required  one-half  ampere  at  45  volts  ; 
consequently  a  greater  pressure  was  required  at 
the  dynamo  to  allow  for  the  "drop"  in  the  con- 
ductors. In  this  last  case  it  required  5  volts, 
making  the  difference  in  potential  at  the  brushes 
of  the  dynamo  50  volts,  the  combined  resistance  of 
the  lamp  and  conductors  being  100  ohms.  Con- 
sequently the  current  consumed  on  the  entire  cir- 

cuit =  —  —  vf   s   =  Vz  ampere.     But  this  %  ampere 
100  ohms 

is  developed  at  a  pressure  of  50  volts.     Therefore, 
it  required  more  power  in  watts,  as  50  volts  X  .5 


HOW   TO   WIRE  BUILDINGS.  29 

ampere  —  25  watts  =  the  power  required  for  lamp 
and  conductor. 

From  this  it  will  be  seen  that  the  question  of 
percentage  of  loss  must  be  carefully  considered,  not 
only  from  a  financial,  but  also  from  an  electrical, 
standpoint. 


30  HOW    TO   WIRE   BUILDINGS. 


CHAPTER  VI. 
PLANS. 

30.  The  plans  generally  used  for  showing  elec- 
tric light  wiring  work  are  what  is  known  as  Floor 
and  Elevation  plans. 

The  Floor  plan  represents  everything  as  being 
flat,  and  on  it  are  .marked  the  outlets,  showing  the 
number  of  lamps  to  each,  and  whether  from  the 
side  or  the  ceiling ;  the  size  and  location  of  the 
wires  forming  the  lamp  circuits  and  the  lamps 
which  are  to  be  connected  to  each ;  also  the  size, 
style  and  location  of  cut-outs  and  switches. 

The  Elevation  plan  should  show  the  number  of 
sets  of  feeders  and  mains,  the  exact  location  of 
points  of  connection  between  the  feeders  and  mains, 
and  between  the  mains  and  sub-mains  which  con- 
nect with  the  lamp  circuits  either  at  the  grouping 
point  or  where  the  cut-outs  are  located  along  the 
ceiling,  as  in  factories  or  in  general  open  work. 
The  style,  size  and  location  of  main  cut-outs  and 
switches  should  also  be  shown.  In  the  ordinary 
two-wire  system  it  is  usual  to  show  only  one  wire, 
it  being  understood  in  this  case  that  the  wires 


HOW    TO   WIRE  BUILDINGS.  31 

forming  the  other  side  of  the  circuit  will  run  par- 
allel with  the  one  shown  on  the  plan,  and  that 
the  cross-section  is  to  be  the  same. 

31.  In  formulating  a  plan  of  wiring  it  is  best  to 
be  familiar  with  the  nature  of  the  structure,  so 
that  the  wires  may  be  fastened  in  places  where  the 
mechanical  conditions  are  favorable. 

While  the  "runs"  should  be  as  straight  and 
short  as  possible,  still  the  drilling  of  walls  and 
partitions  must  be  considered.  In  some  cases  it  is 
cheaper  to  lengthen  the  circuit ;  that  is,  run  the 
wires  at  an  angle  to  those  already  in  place,  so  as 
to  form  a  turn  and  run  somewhat  out  of  the  way, 
or  so  as  to  obviate  the  necessity  of  cutting  through 
a  thick  brick  or  stone  wall ;  or,  in  another  instance, 
to  have  the  wires  free  from  the  interference  of 
steam  pipes,  leaks  of  pipes,  etc. 

It  is  preferable  to  make  an  examination  of  the 
premises  before  laying  out  the  work  on  the  plan. 

The  plan  should  be  arranged  to  show  all  the 
different  circuits  and  appliances  as  plainly  as  pos- 
sible. 

A  good  method  is  to  designate  all  the  different 
cut-outs  and  switches  by  a  letter  of  the  alphabet, 
and  on  a  separate  sheet  or  on  the  margin  of  the 
plan,  refer  to  same.  The  quantity  of  each  appli- 


32  HOW   TO   WIRE   BUILDINGS. 

ance,  and  the  amount  of  each  size  of  wire,  will  in 
this  way  be  an  easy  matter  to  estimate. 

32.  When  the  work  is  completed,  the  plans, 
together  with  any  alteration,  either  in  the  number 
or  change  in  location  of  lights  and  change  of  loca- 
tion or  size  of  wire,  should  be  returned  to  the  com- 
pany. A  report  on  the  changes,  and  by  whose 
authority  the  same  were  made,  should  also  be 
submitted. 


HOW  TO   WIRE  BUILDINGS.  33 


CHAPTER  VII. 


"  CONDUIT  WIRING." 

33.  When  concealing  wires,  either  by  threading 
them  between  the  partitions,  or  under  the  floors, 
or  embedding  them  in  the  plaster,  so  that  when 
covered  they  are  totally  inaccessible,  the  insulation 
is  subject  to  deterioration  and  impairment  due  to 
various  causes  which  may  disarrange  the  lighting 
system  of  the  light  and  cause  failure  or  a  fire. 

It  is  well  known  that  the  best  insulated  wires 
will  withstand  the  action  of  lime,  cement,  alkalies, 
etc.,  for  only  a  short  time.  The  insulation  will 
then  be  useless  for  the  purpose.  The  natural  out- 
come is  that  the  circuit  must  be  rewired,  which 
usually  means  but  a  choice  of  evils. 

The  plaster  must  either  be  cut,  or  the  carpets, 
floor,  etc.,  must  be  torn  up  to  get  at  the  wires. 
The  wires  can  be  run  on  the  surface  and  covered 
with  wood  moulding,  but  this  is  not  desirable  in 
decorated  places.  These  same  conditions  confront 
us  when  additions  or  alterations  are  necessary. 
Buildings  wired  for  so-called  " future  use"  prove, 
in  the  majority  of  cases  where  it  is  proposed  to 


34  HOW   TO   WIRE   BUILDINGS. 

use  the  wiring  a  few  years  after,  to  be  unfit  to  turn 
the  current  on,  and  the  re-wiring  generally  costs 
more  than  the  original  work.  Tinkering  with  the 
wires  already  installed  would  simply  be  false  econ- 
omy. The  materials  used  in  electric  lighting  are 
affected  by  conditions  which  are  not  considered  in 
gas  lighting,  but  there  is  no  reason  why  the  work 
should  not  be  equally  as  permanent  and  successful 
as  good  gas  piping.  This  can  only  be  accomplished 
by  arranging  all  the  conductors  and  appliances  in 
such  a  manner  that  the  whole  wiring  installation 
is  accessible,  but  defacing  the  walls  and  ceiling  is 
objectionable  and  must  not  be  attempted. 

34.  It  is  therefore  necessary  to  locate  the  wires 
in  places  out  of  sight  yet  all  accessible.  To  do 
this  it  is  necessary  to  form  channels  in  the  walls 
and  under  the  floors  for  the  reception  of  the  wires 
exclusively.  The  cheapest,  safest  and  most  prac 
tical  method  is  to  provide  conduits  and  boxes  for 
purposes  of  branching  and  as  receptacles  for  the 
cut  outs  and  switches.  These  boxes  are  also  used 
for  the  purpose  of  withdrawing  or  inserting  wires, 
and  may  be  considered  as  a  hand-hole,  similar  to 
a  manhole  used  for  underground  work. 

The  conduits  not  only  form  an  extra  mechanical 
protection  to  the  wires,  but  also  exclude  those 
elements  which  generally  render  the  insulation  on 


HOW   TO    WIRE   BUILDINGS.  35 

the  wires  worthless.  Ordinarily  it  is  impossible, 
except  at  a  great  expense,  to  change  the  system  of 
lighting  from  the  two  to  the  three- wire  system,  or 
vice  versa,  or,  from  100  to  50-volt  lamps.  The  use 
of  conduits  admits  of  any  practical  change  either 
in  the  system  or  in  the  number  of  lights. 

Buildings  can  be  equipped  with  conduits  (instead 
of  wiring)  for  future  use,  and  the  insertion  of  wires 
is  unnecessary  until  the  actual  time  of  service,  and 
at  a  very  small  increased  cost. 

For  electric  lighting  purposes,  no  wire  should  be 
inserted  in  undefined  channels,  such  as  between 
iioor  and  partition,  because  the  conditions  existing 
in  the  channel  are  unknown ;  they  may  change  at 
any,  time,  and  the  result  is  a  matter  of  chance  and 
peril. 

35.  The  conduit  should  be  constructed  of  such 
materials  as  will  meet  the  requirements  of  the  pur- 
pose, and  the  diameter  of  the  bore  should  be  ample 
for  the  conductor.  They  should  be  installed  in  a 
manner  somewhat  similar  to  that  of  wire.  The 
most  essential  features  to  be  considered  are  ;  the 
completeness  of  system  as  to  points  of  accessibility 
and  absolute  continuity  of  the  tubes  or  wire-ducts. 

The  conduit  system  consists  of  joining  together 
lengths  of  the  tubes,  using  elbows  where  turns  and 
bends  are  necessary.  When  the  length  or  number 


36  HOW   TO    WIRE   BUILDINGS. 

of  turns  or  bends  in  a  circuit  are  such  that  the  in- 
sertion of  the  wire  becomes  difficult,  angle  or  ' '  fish- 
ing" boxes  must  be  provided  so  that  it  will  be  an 
easy  matter  not  only  to  insert,  but  to  withdraw  the 
conductor.  Junction  boxes,  according  to  the  direc- 
tion and  number  of  branches,  must  also  be  pro- 
vided. The  boxes  act  as  a  receptacle  for  the  cut- 
outs, keeping  them  out  of  sight,  and  imparting  a 
finished  appearance  to  the  work. 

The  conduit  must  be  continuous  ;  from  outlet  to 
outlet,  from  box  to  outlet,  and  from  box  to  box. 
Care  must  be  taken  to  have  all  joints,  either  at  the 
coupling  or  the  box,  water-tight,  and  well  insu- 
lated. The  inner  surface  of  the  tube  must  be  in 
alignment  throughout ;  that  is,  no  shoulders  or  im- 
pediments should  be  created,  so  that  the  insertion 
of  the  wires  can  be  done  quickly  and  without 
trouble.  In  a  system  of  conduits  embracing  all 
the  favorable  features,  the  insertion  of  wires  in  the 
conduits  can  be  deferred  until  the  building  is  act- 
ually completed.  The  cut-outs  and  switches  can 
be  inserted  and  connected  at  the  same  time.  The 
metal  parts  will  remain  bright  and  clean,  and  the 
troubles  usually  encountered  in  new  buildings,  due 
to  corrosive  connections,  are  in  this  case  obviated 

The  insertion  of  dra wing-in  strings  at  the  time  of 
installing  the  tubes  must  not  be  relied  upon.  The 


HOW    TO    WIRE   BUILDINGS. 


37 


38  HOW   TO    WIRE   BUILDINGS. 

tube  must  be  considered  empty,  and  installed  in 
such  a  manner  that  should  the  dra wing-in  string 
break,  the  insertion  of  the  wires  can  still  be  easily 
effected. 

Where  the  conditions  are  adverse  to  ordinary 
wiring,  the  use  of  conduits  carefully  installed  will 
generally  meet  all  the  difficulties. 

36.  The  conduits  and  boxes  should  be  located  in 
the  halls  or  public  parts  of  the  building  as  much 
as  possible,  so  that  additions  and  renewals  can  be 
made  without  annoyance  to  the  tenants.  The  bends 
and  turns  should  occur  as  near  the  ends  of  the  lines 
of  conduit  as  possible,  it  being  easier  to  insert  wires, 
more  perfect  control  being  had  over  the  fish  wire. 
The  conduits  should  be  so  arranged  that  a  point  of 
entrance  is  obtained  at  each  outlet,  as  shown  in 
Fig.  1,  so  that  the  work  of  insertion  may  be  quick- 
ly accomplished.  It  also  admits  of  alterations 
being  made  quickly. 

The  system  of  distribution  is  similar  to  the  ordi- 
nary methods  of  wiring.  A  recess  in  the  wall 
should  be  provided  for  the  reception  of  the  main 
and  feeder  line  conduits  exclusively,  provided  with 
a  detachable  cover  throughout ;  or  at  a  certain 
point  on  each  of  the  different  flows,  exactly  as 
shown  in  Fig.  2. 

In  the  figure  showing  tubes  in  recess   A  repre- 


HOW  TO  WIKB  BULLDINGS.  39 


FIG.  2. — CONDUIT  WIRING. 


40  HOW    TO   WIRE   BUILDINGS. 

sents  the  main  tube.  B  represents  the  main  floor 
cut-out,  inserted  in  a  floor  main  junction  box,  C 
represents  the  floor  mains  which  connect  with  the 
lamp  circuits.  Usually  the  main  wires  are  large, 
which  make  it  advisable  to  have  the  cover  of  the 
recess  detachable  the  whole  length.  The  main 
wires  can  be  so  arranged  that  a  pair  are  run  from 
the  dynamo  switchboard  direct  to  each  floor,  or 
the  system  of  distribution  can  be  so  arranged 
that  the  wires  can  be  looped  in  the  conduit,  from 
floor  to  floor,  thus  relieving  the  conduit  of  the 
strain  due  to  the  weight  of  heavy  conduct- 
ors. The  connections  can  be  made  as  shown  in 
Fig.  3. 

In  Fig.  3,  A  represents  main  floor  boxes,  one 
on  each  floor,  to  which  are  connected  the  con- 
duits for  the  main  wires.  The  wires  as  seen  are 
cut  at  each  floor,  so  that  instead  of  starting 
at  A2  and  drawing  the  wires  through  the 
conduit  to  A3,  it  is  only  drawn  from  box  to  box, 
and  the  conductor  is  made  continuous  at  the  cut- 
out connection.  Hence,  if  in  the  future  it  be- 
comes necessary  to  withdraw  the  wire  from  the 
conduit,  between  any  of  the  floors,  it  can  be 
quickly  and  easily  effected.  B  represents  the  main 
feeder  junction  box  with  cut-out  inserted,  for 
means  of  connection  between  the  feeder  and  main 


HOW   TO   WIRE   BUILDINGS. 
A*\ 


41 


FIG.  3.— CONDUIT  WORK. 


42  HOW   TO   WIRE   BUILDINGS. 

wires.  As  this  wire  will  generally  have  a  large 
cross-section,  it  will  be  necessary  to  provide  an 
angle-box  at  C  (which  is  at  the  bend  where  the 
feeders  assume  a  perpendicular  position).  The  an- 
gle-box obviates  the  necessity  of  elbows,  and  at  the 
same  time  performs  the  function  of  a  "fishing 
box." 

The  lamp  circuits  are  divided  in  a  similar  man- 
ner to  that  made  use  of  in  ordinary  wiring.  All  the 
circuits  are  brought  to  a  central  or  grouping  point, 
and  the  conduits  terminate  at  the  box  enclosing 
the  cut-outs,  as  in  the  " Panel"  or  "Closet" 
method.  Judgment  must  be  exercised  in  dividing 
the  circuits  so  that  the  run  from  outlet  to  outlet 
will  not  be  too  long  or  will  not  contain  many  turns 
or  bends. 

37.  One  of  the  most  simple  and  satisfactory 
methods  of  floor  wiring  in  conduiting,  is  shown  in 
Fig.  4,  which  represents  all  the  floor  main  lines  of 
conduits  located  in  the  corridor,  and  at  a  point  near 
the  ceiling.  A  represents  single  branch  junction 
boxes,  fitted  with  a  branch  cut-out,  one  of  each  be- 
ing located  opposite  to  the  room,  whose  lamps  it 
controls.  The  lamp  circuit  is  connected  with  it  and 
is  looped  from  outlet  to  outlet  as  shown  in  Fig  5, 
keeping  each  room  on  one  independent  circuit. 
The  mains  for  the  section  of  rooms  will  be  looped 


HOW   TO    WIRE  BUILDINGS. 


43 


HOW   TO    WIRE   BUILDINGS. 


j 

I 

\ 


WORK 


FIG.  5.  —  CONDU 


HOW    TO    AVI  RE   BUILDINGS.  45 

in  a  similar  manner  from  'A  to  J.,  so  that  provision 
is  made  for  easy  manipulation.  B  represents  the 
main  cut-out  and  junction-box  for  the  section 
through  which  the  floor  main  O  connects  with  the 
section  main ;  D  represents  an  angle-box,  for  use 
at  the  turn,  and  for  making  easy  the  insertion  of 
the  main  wires  in  conduit  C.  E  represents  the 
main  floor  junction-box  and  cut-out. 

By  the  use  of  this  method,  the  pressure  on  the 
wires  can  be  equalized  just  as  nicely  as  in  the 
" Panel"  system.  This  method  tends  to  shorten 
the  distances  between  feeding  points,  manipulation 
is  easier,  and  while  the  cost  of  material  is  not 
increased,  the  amount  of  labor  is  considerably 
decreased. 

38.  When  the  lighting  is  for  general  illumina- 
tion purposes,  that  is,  when  the  lamps  are  turned 
on  or  off  at  the  socket,  as  in  office  buildings,  etc., 
the  lamp  circuits  can  be  installed  in  various  man- 
ners, as  shown  in  Figs.  6  and  7.     The  advantages 
obtained  are,  that  should  the  wire  in  the  cut-out 
(cut-out  link)  fuse,  it  would  only  disconnect  a  por- 
tion of  lamps  located  in  any  one  room.      Also,  it 
will  sometimes  save  material  and  time,  by  shorten- 
ing the  length  of  the  circuits,  and  avoiding  turns 
and  bends. 

39.  The  joints  must  receive  the  same  care  as  the 


46 


HOW   TO    WIRE   BUILDINGS. 


X  4*  x        /"/fear  x  4s  x 


FIG.  6.  —  CONDUIT  WORK. 


HOW    TO   WIRE   BUILDINGS. 


r 


-i 

t 


^ 


i» 


47 


\W\\\J 


I 


48  HOW    TO    WIRE   BUILDINGS. 

• 

joints  on  the  wire,  and  the  conduits  should  be 
handled  in  a  careful  manner.  In  no  case  must  a 
hole  or  break  in  the  conduit  be  patched. 

Not  only  must  the  continuity  of  the  conduit  be 
maintained  throughout,  but  care  must  be  taken  to 
maintain  its  circular  form  also. 

In  concluding  this  chapter  it  may  be  stated  in 
short,  that  the  use  of  conduits  afford  the  only  safe, 
reliable,  and  permanent  method  of  wiring  for  elec- 
tric lighting  and  kindred  purposes. 


HOW   TO   WIRE   BUILDINGS.  49 


CHAPTER  VIII. 

SWITCHBOARDS. 

40.  It  is  preferable  to  make  a  plan,  to  scale, 
showing  all  the  appliances  it  is  intended  to  place  on 
the  switchboard  before  constructing  it,  so  that  suffici- 
ent space  and  insulation  may  be  provided  between 
conductors  of  different,  or  even  of  the  same  polarity. 
The  appliances  and  conductors  should  be  so  ar- 
ranged that,  whether  for  renewals  or  repairs,  the 
different  circuits  can  be  disconnected  without  dis- 
turbing the  remaining  circuits,  and  without  jarring 
or  dislocating  the  board.  The  faceboard  should 
be  constructed  of  materials  that  are  fire  and  moist- 
ure-proof, such  as  marble,  slate,  etc. 

Sufficient  space  should  be  allowed  between  the 
back  of  switchboard  and  the  wall  of  the  room  for 
purposes  of  inspection,  repairs,  etc.,  and  also  that 
should  the  wall  be  damp,  the  switchboard  will  be 
free  from  contact,  and  will  not  have  water  accumu- 
late on  it.  Theatrical  and  converter  switchboards 
should  be  provided  with  a  covering  either  in  the 
form  of  a  door,  or  a  roll,  similar  to  that  of  a  roller- 
top  on  a  desk. 


?~-Lf 


50  HOW   TO   WIRE   BUILDINGS. 

41.  All  switches  and  cut-outs  should  be  equipped 
with  a  suitable  name-plate,  designating  the  partic- 
ular circuit  they  control.     The  name-plate  should 
either  be  fastened  on,  or  directly  under,  the  ap- 
pliance.    In  all  switchboards,  especially  those  used 
in  theatres,  the  switches,   cut-outs  and  other  ap- 
pliances, such  as  regulators,  etc.,  should  be  arranged 
so  that  manipulations  are  quick  and  easy.     Usually 
the  best  plan  is  to  place  the  switches  in  proper 
order  or  sequence,  such  as  1st,  2d,  3d  floors,  etc., 
or  Parquet,  Balcony,  Gallery,  etc.,  in  theatres. 

42.  Dynamo    switchboards    should    be    so    con- 
structed that  all  the  instruments  are  in  plain  sight, 
and  that  the  dynamo  switches  can  be  easily  thrown 
in  or  out,  and  should  be  located  as  near  to  the 
machine  as  possible. 

The  location  of  the  switchboards  should  be  such, 
that  the  plates  or  connecting  parts  on  the  appliances 
will  not  corrode  or  oxidize,  due  to  the  surrounding 
conditions. 


HOW   TO    WIRE   BUILDINGS.  51 


CHAPTER  IX. 


APPLIANCES  AND  CONNECTIONS. 

43.  All  connections,  on  appliances  which  form  a 
part  of  the  circuit,  should  be  kept  clean  and  bright. 
The  stationary  connection  should  be  securely  fast- 
ened; the  sliding  or  movable  connections  should  have 
sufficient  surface,  and  bearing  tension;  and  all  metal 
X>arts  should  have  abundance  of  carrying  capacity  so 
that  undue  heating  will  be  obviated.     The  connec- 
tions should  be  properly  covered  and  protected. 
All  bases  should  be  of  porcelain,  slate  or  similar 
material,  and  all  parts  should  be  so  arranged  that 
access  is  easy.     Switches  should  preferably  be  con- 
structed in  such  a  manner  that  arcing  or  excessive 
sparking  at  the  connections  is  impossible. 

44.  In  joining  or  splicing  wires,  care  should  be 
taken  to  have  the  metal  at  the  point  clean  where 
the  splice  is  to  be  made.     The  connection  must  be 
lirm  and  rigid,  and  thoroughly  soldered  and  insu- 
lated.    The  splice  or  joint  must  be  made  in  such 
manner  that  in  swinging  or  bending  the  wire  the 
sqlder  will  not  crack  or  become  loosened.     In  chap- 
ter V  was  shown  the  relation  of  the  resistance  of 


52  HOW   TO    WIRE   BUILDINGS. 

the  wire  to  the  lamp  circuit,  and  the  amount  of  en- 
ergy expended  in  same,  but  it  was  assumed  that  the 
resistance^was  equally  distributed  along  the  line. 
Should  the  line  or  conductor  contain  an  improperly 
made  joint,  that  is,  one  that  is  loose  or  corroded,  the 
resistance  at  that  point  might  exceed  the  amount  of 
resistance  in  all  the  rest  of  the  line.  The  conse- 
quence would  be  an  abnormal  heating  at  the  joint, 
which  would  gradually  extend  throughout  the 
whole  length  of  the  circuit;  the  current  required  for 
the  lamp  would  be  consumed  in  generating  heat, 
the  candle-power  of  the  lamps  would  decrease,  etc. 

It  is  often  the  case  that  high  grade  wire  is  used, 
and  still  the  insulation  resistance  may  test  low. 
Generally  that  is  due  to  the  careless  manner  in 
which  the  joint  was  insulated. 

The  rule  is  to  have  the  insulation  at  the  joint  or 
splice  equal  to  that  originally  on  the  conductor. 


HOW   TO    WIRE   BUILDINGS.  53 


CHAPTER  X. 


CONVERTER  WORK. 

45.  The  converter  is  practically  an  induction  coil, 
in  which  high  voltage  and  a  small  amount  of  cur- 
rent are  converted  or  transformed  into  low  voltage 
and  a  large  amount  of  current.  The  general  method 
of  constructing  induction  coils  is  :  a  spool  having 
for  its  core  a  bundle  of  tine  iron  wires  ;  a  few  lay- 
ers of  comparatively  coarse  wire  are  then  wound 
on  the  spool,  and  the  ends  turned  out  so  that  con- 
nections with  battery  or  source  of  current  can  be 
made,  over  the  coarse  wire.  Thoroughly  insulated 
from  this  are  wound  a  large  number  of  layers  of 
very  tine  wire,  each  layer  carefully  insulated  from 
the  others.  The  coil  nearest  the  core  is  the  primary 
coil,  and  the  outer,  coil  of  fine  wire,  is  the  second- 
ary coil.  When  the  primary  coil  is  connected  to  a. 
few  cells  of  battery,  and  the  coil  is  equipped  with 
a  rapid  make  and  break  device,  a  powerful  electro- 
motive force  is  created  in  the  secondary  coil.  The 
iron  core  is  used  for  the  purpose  of  increasing  the 
lines  of  force  that  pass  through  the  coils,  and  is 
composed  of  a  number  of  tine  wires,  to  avoid  the 


54  HOW   TO   WIRE  BUILDINGS. 

waste  or  "Foucault"  currents  which  would  be 
created  in  a  solid  core,  and  which  tends  to  make 
the  coils  act  sluggishly. 

46.  In  the  case  of  the  converter,  the  coils  are 
constructed  in  a  manner  directly  opposite  to  that  of 
the  ordinary  induction  coil.  The  converter  primary 
consists  of  a  small  wire  and  many  layers,  and  the 
secondary  coil  consists  of  a  large  wire  with  a  few 
layers. 

The  amount  of  current  in  amperes  supplied  to  the 
primary  coil  is  small,  but  the  voltage  is  high,  and 
the  current  in  amperes  created  in  the  secondary 
coil,  is  large,  but  the  voltage  is  low.  The  size  of 
the  coil  governs  the  difference  of  potential  and  the 
current  produced,  or,  in  other  words,  the  fewer  the 
number  of  layers  on  the  secondary,  the  greater  the 
•current  in  amperes,  and  lower  the  voltage. 

The  converter  as  applied  in  practice,  is  one  of  the 
most  important  discoveries  appertaining  to  the  art 
of  electric  lighting,  and  is  destined,  at  an  early 
•date,  to  play  an  even  more  important  part  than  it 
does  at  present.  It  is  therefore  essential  that  wire- 
men  should  familiarize  themselves  with  the  work- 
ings and  construction  of  the  various  types  of  con- 
verters. They  are  usually  located  on  the  roofs,  or 
sides  of  houses,  on  poles,  or  in  the  vaults  of  struc- 
tures where  the  underground  system  is  used. 


HOW   TO   WIRE  BUILDINGS. 


55 


56  HOW    TO   WIRE   BUILDINGS. 

When  placed  outside  of  a  structure,  a  double  pole 
switch  and  cut-out  should  be  inserted  in  the  line  at 
the  point  of  entrance  to  the  building.  When  the 
converter  is  located  in  the  vault  or  cellar,  the  pri- 
mary wires  should  be  thoroughly  insulated  and 
protected  from  leaks,  grounds,  short  circuits,  and 
mechanical  interference  or  dislocation,  and  at  no 
point  should  the  conductor,  or  the  material  sur- 
rounding it,  touch  the  structure.  The  greatest  care 
should  be  taken,  at  the  point  where  the  wires  enter 
the  building,  to  exclude  gases,  moisture,  etc.  The 
insulation  directly  on  the  conductor  should  be  of 
the  highest  grade.  The  conductor  should  be  in- 
serted in  a  conduit  composed  of  insulating  mate- 
rial, and  all  should  be  inserted  in  a  galvanized  iron, 
or  such  like,  pipe.  The  iron  pipe  should  be  fast- 
ened to,  but  kept  free  from,  the  building  by  the 
use  of  strong  iron  arms,  having  a  band  of  insulating 
material  between  them  and  the  iron  pipe  as  shown 
in  Fig.  1.  The  inner  tube  or  insulating  conduits 
acts  as  a  protection  against  the  abrasion  of  the  cov- 
ering directly  on  the  wire,  and  insulates  it  from 
the  outer  iron  pipe.  It  also  admits  of  more  free- 
dom in  handling  the  circuit. 

A  separate  conluit  and  pipe  should  be  provided 
for  each  wire,  and  should  extend  to  a  box  contain- 
ing the  main  cut-out  and  switch.  This  box  should 


HOW    TO    WIRE    BUILDINGS.  57 

be  lire-proof  and  water-tight,  and  should  be  out  of 
contact  with  the  walls  of  the  structure.  Sockets 
should  be  provided  for  the  en  trance  of  the  pipes,  so 
that  the  connection  between  them  will  be  rigid  and 
tight.  The  box  should  be  of  ample  size,  fitted  with 
a  cover  or  door,  which  should  be  kept  locked,  and 
fitted  with  a  panel  of  glass,  so  that  inspection, 
without  exposure,  is  possible.  It  should  be  located 
as  near  the  point  of  entrance,  and  in  as  dry  a 
place  as  possible. 

The  converter  should  also  be  located  as  near  to 
the  point  of  entrance  as  possible,  and  should  be 
enclosed  in  a  box,  which  should  be  constructed  of 
fire-proof  material.  The  box  should  be  kept  free 
from  contact  with  the  building,  in  a  manner  similar 
to  the  switch-box.  It  should  completely  enclose  the 
converter.  The  roof  of  the  box  should  extend  some- 
what over  the  sides  and  act  as  a  water  shed,  and 
ventilating  holes  should  be  cut  in  the  sides.  In 
short,  all  primary  work,  which  is  that  part  begin- 
ning at  the  point  of  entrance,  up  to  and  including 
the  converters,  must  be  kept  free  from  contact  with 
the  walls  or  floors  of  the  building. 

47.  The  distribution  of  current  is  essentially  the 
same  as  in  low  tension  direct  multiple  arc  systems, 
and  the  total  loss  in  the --wires  must  not  exceed  two 
per  cent.  The  circuits  can  either  be  divided  in 


58 


HOW    TO    WIKE    BUILDINGS. 


2 

-dtD — til — 


HOW   TO    WIRE   BUILDINGS.  59 

accordance  with  the  rated  capacity  of  the  converter 
(providing  a  separate  one  for  each  circuit, )  or,  the 
circuits  can  be  brought  to,  and  connected  with 
omnibus  wires  in  the  usual  manner,  and  also  the 
secondary  of  each  converter  connected  to  the  same, 
in  a  manner  similar  to  the  connection  of  dynamos 
in  multiple  as  shown  in  Fig.  2.  Where  converters 
are  to  be  connected  to  wiring  on  the  three-wire  sys- 
tem two  converters-are  necessary.  The  primaries  are 
connected  in  the  usual  manner,  but  the  secondaries 
are  connected  in  series.  The  two  outer  wires  con- 
nect, one  on  each  terminal,  and  the  middle  or  neu- 
tral wires  connect  to  the  wire  between  the  convert- 
ers as  shown  in  Figs.  3  and  4.  Where  the  larger 
sized  converters*  are  used,  they  should  be  set  on  a 
platform,  built  up  and  insulated  from  the  floor ; 
and  the  switchboard  should  be  so  arranged  that 
the  primary  work  is  separated  from  the  secondary 
work.  It  is  preferable  to  construct  two  switch- 
boards, the  backs  facing  each  other. 

In  a  large  converter  plant,  and  where  the  lighting 
is  such  that  the  greater  portion  of  lamps  are  in  use 
only  at  stated  times,  it  is  the  most  economical  to 
arrange  the  wiring  and  converters  in  such  manner 
that  these  particular  lamp  circuits,  including  the 
converters  for  same,  are  only  connected  to  the  pri- 
mary circuit  at  the  time  of  use.  The  primary  and 


60 


HOW   TO    WIKE   BUILDINGS. 


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HOW   TO   WIRE   BUILDINGS. 


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62  HOW    TO   WIRE  BUILDINGS. 

secondary  circuits  of  each  converter  should  be  pro- 
vided with  a  double-poled  cut-out  and  switch  ;  and 
should  more  than  one  converter  be  connected,  the 
primary  circuit  should,  in  addition  to  those  for  each 
converter,  be  provided  with  a  main  cut-out  and 
switch. 

48.  It  is  preferable,  where  converters  are  located 
in  a  building,  to  have  all  cut-outs  located  outside 
of  the  converter. 

In  no  case  must  the  two  wires  forming  the  pri- 
mary circuit,  be  bared  at  the  same  time,  and  in 
close  proximity  to  each  other.  In  splicing  t>r  in- 
stalling work,  only  one  wire  at  a  time,  should  be 
bared.  Care  must  be  taken  in  handling  same,  so 
that  the  body  does  not  complete  the  circuit. 


HOW   TO    WIRE   BUILDINGS.  63 


CHAPTER  XL 


OVERHEAD  WIRING. 

49.  It  is  often  necessary  in  isolated  lighting  to 
connect  the  wires  in  more  than  one  building  to  a 
dynamo,  which  necessitates  pole,  or  outside  work. 
If  the  distance  between  buildings  is  not  great,  the 
best  method  would  be  to  provide  a  separate  line  or 
feeder  for  each,  and  the  wires  can  be  fastened  to 
the  outside  of,  and  suspended  between,  the  build- 
ings. 

It  is  preferable  to  use  the  petticoated  glass  insu- 
lators, instead  of  the  ordinary  porcelain  knot,  for 
this  style  of  work.  They  should  be  kept  free  from 
contact  with  the  building,  and  allowance  must  be 
made  for  swinging,  so  that  the  wire  will  not  strike 
the  building.  They  should  be  separated  sufficient- 
ly, i.  £.,  in  case  of  sag  they  will  not  come  in  contact 
with  each  other.  This  also  prevents  the  accumula- 
tion of  snow  or  ice.  Where  the  wires  enter  or  de- 
part from  a  building,  generally  over  a  door  or  win- 
dow, they  must  be  protected  by  an  extra  covering, 
such  as  an  insulating  tube,  not  only  for  the  purpose 
of  separating  and  insulating  them,  but  also  to  act 


64  HOW   TO   WIRE   BUILDINGS, 

as  a  water  shedder.  The  holes  should  be  bored  at 
an  angle,  having  the  lower  point  toward  the  out- 
side. 

50.  In  work  of  this  kind,  it  is  preferable  to  keep 
the  two  wires  forming  each  circuit,  next  to  each 
other  in  the  same  manner  as  the  circuits  were  in- 
stalled in  the  interior,  so  that  when  the  plant  is 
turned  over  to  the  customer,  his  man,  in  charge  of 
the  work,  will  more  easily  understand  the  system 
of  wiring.     The  liability  of  mistakes,  when  making 
changes,  will  be  lessened. 

51.  In -pole  line  work,  the  poles   should   be  as 
short  as  possible.     In  setting  in  the  ground,  the 
depth  is  governed  by  the  nature  of  soil,  the  height 
of  the  poles,  and  the  weight  of  the  wire.    Generally, 
for  a  30-foot  pole,  4£  to  5  feet  is  sufficient.     Should 
the  ground  be  swampy,  a  good  plan  is  to  excavate 
widely  and  deeply,  to  admit  placing  a  strong  barrel 
in  the  hole,  into  which  the  pole  is  set.     The  barrel 
should  be  filled  and  packed  with  small  stones  and 
sand,  and  the  whole  covered  with  the  dirt.     This 
will  form  a  suitable  foundation  should  the  poles  be 
short  and  the  weight  of  the  wire  not  abnormal. 
The   base   of  the  pole  should  be  about  8  inches 
in  diameter,  and  the  pole  should  taper  somewhat 
towards  the  top.     If  the  poles  are  to  be  longer  than 


HOW    TO   WIRE   BUILDINGS.  65 

30  feet,  a  safe  rule  is  to  increase  the  diameter  of 
the  pole  1  inch  for  every  increase  of  5  feet  in 
length,  up  to  40  feet ;  and  2  inches  in  diameter  for 
every  5  feet  increase  in  length  thereafter.  The  dis- 
tance between  the  poles  must  also  be  considered. 
Chestnut  wood  is  generally  preferred,  although 
cedar  and  Norway  pine  poles .  result  satisfactorily. 

52.  The  cross-arms  should  be  securely  bolted  to 
the  pole,  and  about  6  to  8  inches  be  allowed  be- 
tween wires.     Care  should  be  taken  when  fastening 
the  wires  to  the  insulators,  which  should  be  of  the 
petticoated  pattern,  so  that  the  "tie  wires"  do  not 
cut  the  insulation  on  the  wires.     It  is  preferable  to 
provide  an  extra  protecting  cover  for  the  wires  at 
all  the  insulators. 

53.  The  wires  should  be  arranged  so  that  the  same 
wire  will  be  fastened  to  the  corresponding  pins  on 
each  pole,  throughout  its  entire  length.     The  dis- 
tance between  poles  depends  upon  the  weight  and 
size  of  the  wire.     A  fair  average  distance  would  be 
200  feet. 


66  HOW   TO   WIRE   BUILDINGS. 


CHAPTER   XII. 


FUSE  WIRE. 

54.  The  fuse  wire  is  to  an  electric  lighting  system 
or  plant  what  the  safety  valve  is  to  a  system  of 
steam  generation  and  supply.     The  wire  for  fuses 
is  composed  of  an  alloy  of  tin,  lead,  etc.,  and  to 
properly  perform  its  functions  should  never  be  con- 
nected in  a  circuit  carrying  in  amperes  more  or  less 
than  the  rated  carrying  capacity  of  the  fuse  wire. 
That  is  :  never  use  a  10-ampere  fuse  in  a  5-ampere 
circuit  or  vice  versa.     Never  make  any  allowance  in 
the  carrying  capacity  of  the  fuse  wire.     It  has  al- 
ready been  tested  and  standardized  by  the  manu- 
facturers. 

55.  The  fuse  wires  are  connected  in  the  circuit 
by  means  of  a  cut-out  block,  and  when  grounds, 
crosses,  or  excessive  leakage  occur,  the  current  in- 
creases to  such  an  extent  that  the  conductors  be- 
come unduly  heated,  due  to  their  resistance.     The 
nature  of  the  fuse  wire  being  such  that  it  will  melt 
at  a  lower  temperature  than  the  copper  wire,  it  will 
in  the  event  of  an  occurrence  of  this  kind,  melt, 
thereby  automatically  opening  or  breaking  the  cir- 


HOW   TO    WIRE   BUILDINGS.  67 

cuit.  If  the  fuse  wire  is  too  small,  it  will  fuse  un- 
necessarily, which  is  a  source  of  annoyance  ;  but 
should  the  fuse  wire  be  too  large,  it  will  only  melt 
after  the  load  becomes  too  great,  at  which  time  the 
line  and  dynamo  are  so  hot  that  the  insulation  is 
affected,  or  the  resistance  of  the  copper  wire  in  case 
of  electrolytic  action,  will  be  greater  than  that  of 
the  fuse  wire  (making  allowance  for  the  difference 
of  melting  points),  in  which  case  the  wire  will  melt 
and  may  form  an  arc.  In  the  event  of  an  occur- 
rence of  a  short  circuit  or  heavy  ground,  if  no  pro- 
vision in  the  shape  of  fuse  wires  had  been  made, 
the  line  or  armature  would  melt. 

The  importance  of  using  only  fuse  wires,  that  are 
standardized,  is  evident. 

Never  assume,  unless  the  fuse  wires  have  been 
supplied  by  the  same  manufacturer,  that  because 
the  cross-section  is  the  same  in  the  case  of  two  fuse 
wires,  their  rated  capacity  or  fusable  point  is  the 
same.  The  fusing  point  of  the  wires  is  governed 
by  the  proportions  of  the  different  metals  forming 
the  alloy,  and  although  both  of  the  above-men- 
tioned wires  may  have  had  sufficient  carrying 
capacity  for  the  particular  circuit,  the  fusing  points 
may  have  been  different. 

56.  In  the  case  of  a  short-circuit  the  fuse  wire, 
even  though  somewhat  larger  than  necessary,  will 


68  HOW   TO   WIRE   BUILDINGS. 

melt,  but  short-circuits  is  not  the  only  element  to 
guard  against.  Leaks  and  grounds  are  just  as  liable 
to  occur,  and  the  rating  of  the  fuse  wire  must  be  in 
accordance  with  these  liabilities.  To  explain  the 
function  of  the  fuse  wire  more  clearly,  it  may  be 
said  that  if  in  a  piping  system  for  water,  steam, 
etc.,  the  pipes  should  be  overloaded,  they  will 
break  or  burst  at  the  weakest  point.  In  a  wiring 
system,  instead  of  bursting,  the  conductor  will  melt 
at  the  point  which  is  weakest.  To  prevent  this 
happening  in  the  dynamo  and  conductors,  is  the 
function  of  the  fuse  wire.  Its  cross-section  or  car- 
rying capacity,  therefore,  is  figured  only  for  the 
current  necessary  for  consumption  in  the  lamps, 
and  should  any  increase  occur,  the  wire  will  at 
once  melt  and  disconnect  the  circuit.  The  question 
of  fuse  wires  should  also  be  considered  from  a 
financial  standpoint.  Should  they  be  too  large, 
and  a  ground  occur,  the  dynamo  is  not  only  gener- 
ating the  current  consumed  by  the  lamps,  but  also 
that  which  is  wasted  through  the  ground,  and 
should  it  be  in  a  system  in  which  the  dynamo  is 
already  heavily  taxed,  this  additional  amount 
which  is  wasted,  will  cause  an  abnormal  drop  in 
potential,  or  still  worse,  burn  out  the  armature. 
The  only  method,  whose  prompt  action  can  be  as- 
sured, is  the  use  of  fuse  wires,  the  capacity  and 


HOW    TO    WIRE    BUILDINGS.  69 

fusibility  of  which  has  been  carefully  tested  and 
standardized. 

57.  The  insertion  of  fuse  wires  in  circuits,  is  of 
too  great  importance  to  be  a  matter  of  chance  or 
guess-work,  and  wiremen  should  never  use  fuse 
wire  or  links,  other  than  that  supplied  by  the  par- 
ticular company  or  contractor,  in  whose  employ 
they  are  at  the  time,  because  the  distance  between 
the  screws  on  the  cut-outs  may  be  greater  or  less 
than  for  those  used  by  other  companies.  This  will 
change  the  carrying  capacity  of  the  fuse  wires. 
Or,  again,  the  alloy  may  be  different. 


70  HOW   TO    WIRE   BUILDINGS. 


CHAPTER  XIII. 


INSULATION. 

58.  Conductors  are  insulated  for  the  purpose  of 
harnessing  or  controlling  the  current,  so  that  it 
can  be  directed  in  a  certain  defined  path,  which  is 
generally  wire  composed  of  copper.  In  addition  to 
its  inability  to  transmit  current,  the  insulation 
should  be  absolutely  moisture-proof,  and,  if  possi- 
ble, fire-proof. 

Rubber,  and  compounds  composed  principally 
of  rubber,  are,  for  practical  purposes,  the  best. 
Rubber  is  elastic,  and  can  be  bent  without  injury. 
Being  moisture-proof,  it  acts  as  a  safeguard  against 
the  worst  element  of  trouble  (see  Electrolysis). 
Although  not  fire-proof,  it  will  withstand  high 
temperature  without  melting.  This  material  being 
also  naturally  delicate,  is  protected  and  strength- 
ened by  an  outside  covering,  which  is  generally 
composed  of  fibrous  material,  treated  chemically, 
so  that  it  becomes  to  a  great  extent  fire-resisting. 
The  outer  covering  is  not  relied  on  for  its  insulating 
qualities,  but  more,  from  a  mechanical  standpoint, 
as  a  protection  against  abrasions,  etc.  Experience 


HOW   TO   WIRE   BUILDINGS.  71 

and  time  has  demonstrated  that,  protection  against 
moisture,  is  a  prevention  of  lire  ;  and  the  best  re- 
sults for  interior  work,  have  been  obtained  when 
the  wires  were  insulated  by  a  material  similar  to 
that  mentioned. 

59.  To  secure  permanence,  the  quality  of  the  in- 
sulation must  be  of  the  best,  and  absolute  contin- 
uity must  be  maintained.  The  minutest  crack, 
bruise,  or  pin-hole  is  sure,  sooner  or  later,  to  create 
trouble.  It  must  be  handled  with  the  utmost  care, 
and  the  small  amount  of  extra  time  spent  in  care- 
ful handling,  will  more  than  offset  the  time  and 
trouble  that  would  be  needed  to  locate  and  repair 
insulation  damaged  by  carelessness.  The  manu^ 
facture  of  high  grade  wire  of  this  nature,  appre- 
ciating the  importance  of  the  subject,  use  the  ut- 
most care  and  vigilance  in  its  manufacture.  It  is 
one  continual  round  of  inspection  and  testing,  from 
the  start  to  the  finish.  When  the  wires  are  made 
up  in  coils,  they  receive  the  final  test,  and  if  found 
to  be  up  to  the  standard,  are  made  ready  for  market. 
The  same  care  is  exercised  in  the  packing  and  ship^ 
ping,  and  if  equal  pains  were  taken  after  the  wire 
left  the  manufacturer's  hands  little  trouble  would 
be  experienced,  due  to  defective  insulation.  The 
greatest  source  of  danger  is  the  rough  usage  it 
receives  at  the  hands  of  inexperienced  or  careless 


72  HOW   TO   WIRE   BUILDINGS. 

wire-men.  Another  source  of  trouble  is,  insufficient- 
ly insulated  joints  or  splices.  When  baring  the 
wire  to  make  a  joint,  the  insulation  should  not  be 
torn  off,  or  cut  in  a  manner  similar  to  whittling 
wood.  It  should  be  cut  at  right  angles  to,  and 
neatly  severed  from,  the  conductor,  and  then  slit 
open  between  the  points  cut.  It  will  then  be  an 
easy  matter  to  remove  the  insulation,  without  strain- 
ing it  on  either  side  of  the  exposed  part.  In  solder- 
ing, care  should  be  taken  to  keep  the  insulation 
free  from  the  acid  and  fiame. 

60.  When  the  splice  is  made,  it  should  be  insu- 
lated in  a  manner  equal  to  that  on  any  other  part  of 
the  line.  This  is  usually  accomplished  by  the  use 
of  a  strip  of  rubber  compound,  wound  or  wrapped 
around  the  joint,  starting  at  a  short  distance  back 
from  the  splice,  and  on  the  insulation.  In  wrap- 
ping the  tape  it  should  be  wound  at  an  angle,  so 
that  each  of  the  layers  will  lap  over  one-half  of  the 
preceding  wraps.  This  provides  a  double  thick- 
ness. If  the  conditions  are  adverse,  an  extra  wrap- 
ping should  be  provided,  and  placed  over  the  first, 
in  such  a  manner  that  the  laps  of  the  second  cover- 
ing cross  the  laps  of  the  first.  The  heat  of  the 
hand  is  generally  sufficient  to  cause  the  material  to 
adhere  and  form  a  solid  mass.  Over  all  should  be 
placed  a  tape  of  linen  or  such  material,  impregnated 


HOW   TO    WIRE   BUILDINGS.  73 

with,  rubber.  When  taping  splices  on  exposed 
lines  in  a  perpendicular  position,  the  wrapping 
should  be  started  at  the  bottom  of  the  splice  and 
worked  towards  the  top.  In  this  manner  the  tape 
will  act  as  a  shedder. 

61.  In  molding  work,  the  grooves  should  be  sufi> 
ciently  large  to  admit  the  wire  easily,  without  being 
forced  in.  When  fastening  wires  to  porcelain  in- 
sulators with  tie  wires,  an  extra  wrapping  of  tape 
should  be  put  over  the  wires  at  those  points,  and 
care  taken,  that  the  tie  wires  do  not  bruise  or  dis- 
rupt the  insulation.  The  more  recent  styles  of  por- 
celain insulators  obviate  the  use  of  tie  wires,  and 
for  this  reason  are  a  great  improvement.  Forcing 
wires  in  or  around  sharp  corners  is  not  recom- 
mended, and  should  be  done  with  the  greatest  care. 

When  uncoiling  wire,  be  careful  not  to  get  a  sharp 
kink  in  it.  Should  a  defect  in  the  insulation  of  a 
coil  of  wire  be  discovered,  the  whole  coil  should 
be  put  aside  and  subjected  to  a  test  before  any  part 
is  used.  In  new  buildings  especially,  the  greatest 
care  should  be  exercised.  Avoid  having  the  wire 
either  in  coils,  or  strung  out,  lying  on  the  floor, 
while  using.  The  floor  is  generally  covered  with 
mortar,  brick,  and  other  sharp  or  rough  materials  ; 
mechanics  are  constantly  moving  about,  and  the 
fall  of  a  brick,  or  a  barrow  wheeled  over  the  wire, 


74  HOW   TO   WIRE   BUILDINGS. 

, 

is  generally  all  that  is  necessary  to  impair  the  in- 
sulation. The  defect  may  not  show  at  the  time,  but 
sooner  or  later  it  is  bound  to  be  the  source  of 
trouble.  When  passing  wires  through  walls,  floors, 
partitions,  etc.,  a  tube  of  insulating  material  should 
first  be  inserted,  so  that  there  may  be  no  danger  of 
tearing  the  insulation  as  it  is  passed  through. 

62.  For  pole  line  or  outside  work,  a  strong  and 
durable  weather-proof  covering  should  be  placed 
over  the  insulation. 

The  quality  of  insulation  can  only  be  determined 
by  tests,  and  practical  application,  but  to  form  a  fair 
estimate  of  the  quality  simply  by  inspection,  in  a 
general  way,  it  may  be  said  that :  the  insulation 
should  be  tough  and  lively,  that  is,  it  should  not 
resemble  leather  in  the  quality  of  its  toughness,  but 
should  possess  more  elasticity,  and.  when  stretched 
and  suddenly  released,  it  should  quickly  assume 
its  previous  shape.  If  when  pulled  in  opposite 
directions,  it  parts  without  stretching,  somewhat  as 
dry  putty  or  dough  would,  it  is  inferior.  The  best 
grades  have  two  layers  of  insulation,  an  inner  white 
or  red,  and  an  outer  black,  core,  and  an  additional 
covering  of  braid  or  tape  over  all.  The  advantage 
of  the  special  inner  layer  is  the  prevention  of  the 
oxidization  of  the  conductor  ;  and  should  the  outer 
layer  become  bruised  or  impaired,  the  wire  is  still 


HOW   TO   WIRE   BUILDINGS.  75 

protected  by  the  inner  layer.  The  best  manner  in 
which  to  make  the  superficial  tests,  as  explained,  is 
to  cut  a  small  strip  of  insulation  from  the  wire, 
divesting  it  of  the  tape  or  braid. 

Another  method  of  testing  for  toughness,  is  : 
Taking  a  piece  of  No.  14  wire  insulated,  twist 
and  bend  it,  until  either  the  wire  or  the  insulation 
is  broken. 

In  a  first-class  insulated  wire,  the  copper  will 
break,  and  the  insulation  will  remain  intact. 


76  HOW   TO    WIKE   BUILDINGS. 


CHAPTER  XIV. 


ELECTROLYSIS. 

63.  In  discussing  this  subject,  it  will  be  treated 
only  with  a  view  of  showing  its  relation  to  Electric 
Light  Wiring.  While  it  is  really  a  part  of  the 
previous  chapter,  it  was  considered  too  vital  to 
be  merely  mentioned.  It  is  of  the  utmost  import- 
ance that  wiremen  and  others  interested  in  con- 
struction work  should  be  familiar  with  the  subject. 

Wires  are  also  insulated  for  the  purpose  of  pre- 
venting electro-chemical  action.  The  word  "  Elec- 
trolysis" means  Electrical  analysis,  or  analyzing 
with,  or  by,  the  use  of  electricity.  All  liquids, 
with  the  exception  of  oils,  are  fair  electrical  con- 
ductors, and  under  certain  conditions  even  oil  will 
lose  its  insulating  qualities  to  a  great  extent. 

Insert  the  wires  forming  both  sides  of  a  battery 
circuit,  each  into  a  glass  tube,  closed  at  one  end 
and  nearly  filled  with  water,  invert  same  into  a 
larger  jar,  into  which,  water  must  also  be  poured. 
The  larger  jar  should  be  so  arranged  that  the  wires, 
composed  of  platinum,  will  not  come  in  contact 
with  the  water  in  same ;  the  use  of  the  platinum 


HOW    TO    WIRE   BUILDINGS.  77 

prevents  oxidization  of  the  terminals.  In  complet- 
ing the  circuit,  through  the  water,  decomposition 
of  the  water  ensues.  Water  being  composed  of 
hydrogen  and  oxygen,  it  will  in  short  be 
found  that  these  gases  have  been  generated,  the 
hydrogen  in  one  tube,  and  the  oxygen  in  the  other, 
and  in  proportion  to  their  relative  quantities.  The 
separation  or  decomposition  is  caused  by  the  ac- 
tion of  the  current  when  flowing  through  the  water. 
Instead  of  using  platinum  wire  and  two  tubes 
and  a  jar,  we  will  change  the  experiment  somewhat. 
We  will  take  a  jar  filled  with  water  into  which  are 
placed  the  ends  of  two  pieces  of  ordinary  copper 
wire,  connected  to  battery.  When  the  current  is 
turned  on,  the  water  completes  the  circuit.  In  this 
case  not  only  is  the  water  decomposed,  but  the 
copper  also.  The  wire  forming  the  positive  pole 
will  be  decomposed  and  the  atoms  will  be  carried 
through  the  water  to  the  negative  wire.  This 
action  in  electric  lighting  is  sometimes  termed  a 
" partial  short-circuit,"  and  if  the  resistance  of  the 
conductor,  either  liquid  or  metallic,  is  lower  than 
that  of  the  fuse  wire,  the  latter  will  melt  and  so 
disconnect  the  circuit. 

64.  The  most  common  causes  of  electrolysis  are, 
defective  insulation  on  the  wire  ;  joints  insufficient- 
ly insulated,  excessive  and  continuous  moisture, 


73  HOW    TO    WIRE   BUILDINGS. 

etc.  With  insufficiently  insulated  wire  located  in 
or  fastened  to  a  damp  or  moist  wall,  the  amount  of 
current  escaping  or  leaking  may  at  first  be  very 
small,  but  the  action  of  the  current,  and  the  oxide 
from  the  copper,  in  a  short  time  render  the  insula- 
tion absolutely  worthless.  The  leak  increases,  and 
the  current  flowing  through  the  copper  wires,  which 
are  immersed  in  water,  will  create  the  chemical 
action,  as  explained.  The  copper  will  be  decom- 
posed, and  dissolves  away  into  the  water.  Copper 
oxidizes  rapidly,  and  the  wire  at  this  point,  will  in 
a  short  time  be  wholly  decomposed.  The  greater 
the  current  and  the  lower  the  resistance  of  the 
moisture,  the  quicker  this  will  be  accomplished. 

Where  this  defect  occurs,  the  action  is  as  follows: 
If  the  resistance  of  the  moisture  or  liquid  between 
the  poles,  is  as  low  as,  or  lower  than,  the  resistance 
of  the  fusible  strip  used  in  the  cut-out,  the  result 
will  be  the  same  as  in  a  short-circuit ;  that  is,  the 
fuse  will  melt.  But  should  the  resistance  of  the 
moisture  be  far  greater  than  that  of  the  fuse  wire, 
the  decomposition  of  the  wire  will  gradually  be  ac- 
complished, and  as  it  advances,  the  heat,  and  loss 
of  electrical  energy  in  the  conductors  increases,  the 
lights  become  dimmer,  and  the  carrying  capacity 
of  the  wire  decreases,  to  the  poin.t  where  it  melts 
instead  of  the  fuse  wire  in  the  cut-out. 


HOW   TO    WIRE   BUILDINGS, 


79 


In  other  instances,  the  wire  will  be  so  decomposed 
and  so  thin  that  at  a  certain  point  it  is  as  fine  and 
sharp  as  an  ordinary  needle,  and  a  slight  vibration 


FIGS.  1,  2  and  3.— ELECTROLYSIS. 

of  the  building  will  cause  the  wire  to  part,  and  an 
arc  to  occur. 

65.  The  foregoing  proves  the  importance  of  prop- 
erly fusing  the  circuits,  and  using  only  the  best 
sjrade  of  materials.  The  best  and  most  effective 
method  of  obviating  the  danger,  is  to  use  conduits, 
and  high  grade  moisture-proof  wires  throughout, 
providing  a  separate  tube  for  each  wire,  and  ex- 
cluding moisture  at  the  joints,  etc. 


80  HOW   TO   WIRE   BUILDINGS. 


CHAPTER  XV. 


ADVERSE  WIRING  CONDITIONS. 

66.  Where  adverse  conditions  exists,  such  as 
moisture  and  gas,  the  best  results  have  been  ob- 
tained by  stringing  the  wires,  fastened  to  suitable 
insulators,  on  the  face  of  the  walls,  etc.  The  in- 
sulators should  be  as  few  as  possible.  The  iixtures 
and  wires  should  be  kept  free  from  contact  with 
the  building.  The  cut-outs  and  switches  should  be 
located  in  a  clean  dry  place,  and  to  accomplish  this, 
the  length  of  the  circuits  must,  if  necessary,  be  in- 
creased. The  fixture,  if  one  is  necessary,  should 
consist  of  a  metallic  pipe,  and  the  wiring  of  the 
fixture  must  be  two  heavily  insulated  wires.  The 
end  of  the  pipe  toward  the  outlet  should  be  closed 
by  a  cork,  putty,  or  insulating  compound.  The 
socket  and  lamp  should  be  enclosed  in  a  water-tight 
globe.  Key  sockets  should  never  be  used,  but  all 
circuits  be  controlled  by  switches.  The  fixture 
should  from  time  to  time,  be  treated  to  a  coat  of 
preservative  p&int. 

In  fixtures  placed  on  the  outer  walls  of  a  build- 
ing, the  stem  or  pipe  should  extend  through  the 


HOW   TO   WIRE   BUILDINGS.  81 

entire  thickness  of  the  walls,  and  the  electrical  con- 
nections be  made  in  the  interior  of  the  building. 

All  shades  on  outside  fixtures  should  be  of  the 
hood  pattern,  and  be  provided  with  an  inner  shell 
or  cover,  so  that  the  socket  and  lamp  connections 
are  protected  from  the  elements. 

67.  If  conduits  are  resorted  to,  the  same  general 
directions  must  be  followed,  and  care  must  be  taken 
to  exclude  moisture  and  gas  from  the  interior  of 
the  tubes. 

Stables. — The  chief  trouble  in  stables  is  due  to 
the  ammonia  which  is  generated  in  the  stalls.  The 
moisture  and  exposure  also  affect  not  only  the  in- 
sulation on  the  wires,  but  corrode  all  the  metallic 
parts  of  the  fixture  and  the  line  appliances.  There- 
fore the  weakest  points  are  at  the  joints,  sockets, 
cut-outs  and  switches,  and  connection  between  the 
fixture  and  circuit  wires. 

Breweries. — The  conditions  are  somewhat  similar 
to  those  which  exist  in  stables,  and  in  some  por- 
tions of  the  structure,  excessive  moisture  exists  at 
all  times.  In  other  portions,  the  temperature  is 
extremely  high,  and  in  still  other  parts,  very  low 
temperature  exists.  The  same  care  must  be  taken, 
as  outlined  in  the  general  directions,  and  in  the 
fermenting  room,  if  the  conditions  are  unusually 
severe,  double  petticoated  glass  insulators  set  on  a 


82  HOW    TO   WIRE   BUILDINGS. 

bridge  or  collar,  suspended  from  the  ceiling  should 
be  used,  and  the  wires  fastened  thereto.  The 
bridge  or  collar  should  be  treated  to  at  least  two 
coats  of  preservative,  insulating  paint.  The  fix- 
ture wire  should  be  of  the  same  size  as  that  on  the 
lamp  circuit,  and  the  lamp  circuit  should  be  con- 
trolled by  a  switch  and  cut-out  only,  located  in 
some  suitable  place.  For  the  mains  and  feeders, 
conduits  are  recommended.  If  conduits  are  used 
throughout,  care  must  be  taken  to  keep  the  interior 
of  the  tubes  free  from  moisture,  gas,  etc. 

Oil  Works,  Etc. — If  the  conditions  are  such  that 
the  oil  does  not  leak  through  the  floor  excessively, 
then  a  general  observance  of  the  succeeding  direc- 
tions is  all  that  is  necessary.  In  some  cases  the 
buildings  are  of  the  ramshackle  sort,  and  the  oil 
leaks  freely  through  the  floors.  Where  the  leak- 
age is  thus  excessive,  the  only  safe  method  is  to 
provide  a  continuous  shedder,  for  the  line  and  fix- 
tures, consisting  of  tin,  heavily  coated  with  non- 
corrosive  paint.  The  hood  or  shedder  should  be 
suspended  from  the  ceiling,  and  the  conductors  be 
kept  free  from  contact  with  the  building. 

Where  explosive  gases  are  generated,  or  where 
paints,  naphtha,  and  such  materials  are  used  or 
stored,  the  conductors  should  be  kept  free  from 
contact  with  the  building,  and  be  exposed  as  much 


HOW   TO   WIRE   BUILDINGS.  83 

as  possible,  care  being  taken  to  provide  against  the 
accumulation  of  gases,  etc.,  at  any  point.  The 
fixture  wire  must  be  connected  directly  to  the 
lamp-circuit  wires,  omitting  the  cut-out.  All  the 
circuits  must  be  controlled  by  a  double-pole  cut-out 
and  switch  only,  and  the  same  must  be  located 
where  the  conditions  are  most  favorable. 

68.  In  all  such  cases  as  those  mentioned,  the  use 
of  conduits  on  the  mains  and  feeders  is  recom- 
mended. In  no  case  must  wires  be  moulded  or 
cleated.  Either  large  porcelain  knobs  or  glass 
insulators  must  be  used. 

Insulated  wires,  of  any  sort,  must  never  be  im- 
bedded directly  in  plaster  ;  and  where  alkalies,  or 
acids  exist,  an  extra  covering,  such  as  conduit, 
must  be  provided. 

Avoid  placing  wires  under  tiled  floors,  etc. 
Floors  of  this  kind  are  usually  cleaned  with  sul- 
phuric acid,  which  being  absorbed  by  the  tile  and 
cement,  attacks  the  insulation. 

In  prisons,  asylums,  etc.,  the  wires,  lamps  and 
appliances  must  be  inaccessible  for  the  inmates, 
but  the  switches  and  cut-outs  must  be  located  in  a 
place  easy  of  access  for  those  in  charge.  All  the 
cut-outs  and  switches  controlling  particular  circuits 
on  the  different  floors  should  be  located  in  a  place 
and  manner  corresponding  to  the  conditions  on  the 


£4  HOW   TO   WIKE   BUILDINGS. 

other  floors.  This  will  tend  to  simplify  matters, 
and  will  not  confuse  the  attendant,  when  it  is 
necessary  for  some  reason  to  turn  on  the  lights 
quickly. 


HOW   TO    WIRE   BUILDINGS.  85 


CHAPTER  XVI. 

THEATRE  AND  STAGE  LIGHTING. 

69.  In  theatre  wiring,  the  wires,  cut-outs  and 
switches  should  be  located  in  places  out  of  the 
reach  of  inexperienced  or  malicious  persons,  but  at 
the  same  time  of  easy, access  to  those  having  charge. 
The  cut-outs  and  switches  should  be  grouped  in  as 
few  places  as  possible,  so  that  the  turning  on  or  off 
of  lights  may  be  quickly  accomplished.  All  the 
lights  in  the  theatre  proper  and  stage  should  be 
controlled  by  switches  at  the  stage  switchboard. 
The  circuits  controlling  lights  in  the  dressing- 
rooms,  cellar,  and  such  places,  should  also  ramify 
or  branch  out  at  this  point. 

The  public  lights,  that  is  :  the  lights  on  the  side- 
walk, entrances,  lobbies,  foyers,  waiting-rooms, 
etc.,  should  be  connected  to  switches,  all  at  one 
point,  and  controlled  from  the  front  of  the  house, 
usually  in  or  near  the  ticket  office,  or  foyer.  These 
circuits  should  be  connected  with  a  separate  feeder 
direct  from  the  source  of  supply,  and  independent 
of  the  circuits  for  the  lights  in  the  theatre  proper. 


86  HOW   TO    WIRE   BUILDINGS. 

70.  The  lights  in  the  auditorium  are  located  in 
the  dome  ;  proscenium  arch  ;  side-lights  in  the  gal- 
lery, balcony,  and  parquet,  and  in  the  private 
boxes  ;  the  front  of,  or  face  of  the  gallery  ;  bal- 
cony and  boxes  ;  and  on  the  stage.  All  the  circuits 
for  these  lights,  except  the  stage  lights,  are  gen- 
erally connected  to  the  same  regulator. 

The  lights  for  the  orchestra  or  band,  are  placed 
in  deep  metal  shades,  painted  green  on  the  outside, 
and  white  on  the  inner  surface,  so  that  when  the 
lights  throughout  the  house  are  turned  down,  or 
dimmed,  the  glare  of  the  music  lights  will  not 
counteract  the  effect. '  They  must  be  arranged  so 
that  the  light  is  reflected  on  the  music  only.  The 
method  of  distribution  is  generally  as  follows : 
Separate  feeders,  extending  from  the  switchboard 
on  the  stage,  are  carried  to  the  centre  of  each  cir- 
cuit, at  which  point  the  feeder  terminates  into  a 
double  branch  cut-out,  and  the  lamp-circuit  wires 
are  carried  to  the  different  lamps  on  the  circuit. 

A  good  plan  is  to  provide  a  separate  circuit,  con- 
necting with  a  switch  and  cut-out  at  the  stage 
switch-board  with  the  : 

Gallery  side  lights. 

Balcony  side  lights. 

Parquet  side  lights. 

Gallery  "face"  lights. 


HOW   TO   WIRE  BUILDINGS.  87 

Balcony  "face"  lights. 

Private  box  lights,  outside  of  dome  lights,  gen- 
erally two  circuits  ;  proscenium  arch  lights,  two  cir- 
cuits. If,  in  addition  to  the  side  lights  in  the 
house,  chandelier  or  ceiling  lights  are  placed  in  the 
rear  of  each,  a  separate  circuit  for  each  floor  should 
be  provided,  and  run  similarly  to  the  side  light 
circuit. 

71.  The  rate  of  loss  in  the  conductors  is  usually 
computed  at  5  per  cent.,  and  divided  as  follows  : 
1  per  cent,  loss  in  the  lamp  circuit,  H  per  cent,  loss 
in  the  feeder  from  stage  switch  board  to  the  centre 
of  distribution  of  lamp  circuit,  and  2\  per  cent,  loss 
in  the   feeders   from  the  dynamo-room   or    other 
source  of  supply.     The  stage  lights  generally  con- 
sist of  the  foot,  borders,  bunch,  entrance,  ground, 
projecting,  and  such  other  lights  as  may  be  used 
for  scenic  or  other  effects  ;  and  a  few  '  *  working ' ' 
lights. 

72.  The  foot  lights  generally  consist  of  three  cir- 
cuits, provided  with  the  plain  red  and  green,  or 
blue  glass  bulbs,  respectively.     The  position  and 
construction  of  the  fixture  or  reflector,  and  the 
lamps,  should  be  such  that  the  lamps  are  out  of  the 
line  of  sight,  and  the  reflector  so  placed  that  the 
view  from  the  auditorium  will  be  wholly  unob- 


HOW   TO   WIRE   BUILDINGS. 


structed.  The  lamp  should  be  placed  close  to  the 
reflector,  and  in  such  a  manner  that  the  light  is 
reflected  on  the  stage.  In  addition  to  the  electric 
lights,  provision  is  made  for  gas  lighting,  and 
as  the  space  is  limited,  the  work  should  be  so 
arranged,  that  in  the  event  of  the  gas  being  lighted, 
the  excessive  heat  will  not  affect  the  electric  work. 
A  satisfactory  method  is  to  construct  the  foot  lights 
in  a  manner  similar  to  that  shown  in  Fig.  1.  The 


lamp 

Socket 
Mouldnig 

Timber 


Stageftoor 


GasPipe 


FIG.  1. — THEATEE  LIGHTING. 

work  is  located  under  the  stage,  where  dislocation 
is  improbable,  and  is  securely  fastened  so  that  only 
the  bulbs  of  the  lamps  are  visible.  The  work  is 
covered  and  protected  by  heavy  sheet  tin,  and  holes 
are  cut  to  correspond  with  the  entrance  of  the 
sockets. 

This  method  will  allow  of  placing  a  large  number 
of  lamps  in  one  row.  The  three  circuits  are  so 
arranged  that  the  colors  will  alternate. 


HOW   TO   WIRE  BUILDINGS.  89 

Another  method  is,  placing  the  wires  on  the  out- 
side of  the  reflector,  having  a  frame  work  of  wood, 
and  placing  the  lamps  at  an  angle,  as  shown  in 
Fig.  2.  These  circuits  are  connected  to  the  regu- 

Stageft+a* 


Fm.  2. — THEATRE  LIGHTING. 

lating  device,  either  separately,  or  arranged  so  that 
one  regulator  can  be  used  for  either,  and  the  num- 
ber is  governed  by  the  width  of  the  opening— 
usually  as  many  a3  can  be  placed  without  crowd- 
ing. The  inner  surface  of  the  foot  light  reflector 
should  be  coated  with  either  white  paint  or  lime. 

73.  Border  lights  are  rows  of  lights  located  in  a 
reflector,  and  suspended  between  the  curtains  in 
the  "  flies,"  and  high  enough  to  be  out  of  the  sight 
of  the  audience ;  they  are  used  for  lighting  the 
body  and  back  of  the  stage,  scenes,  etc.  The 
reflector  is  formed  to  throw  the  light  in  the  direction 
mentioned,  and  also  prevents  the  light-giving 
medium  from  being  seen  in  the  front  of  the  house. 


90  HOW   TO   WIRE  BUILDINGS. 

Each  border  usually  consists  of  one  row  of  plain 
glass  bulbs,  and  the  number  of  rows  and  lamps  on 
each  is  governed  by  the  width  and  depth  of  the 
stage,  and  the  number  of  side  entrances.  Usually 
five  rows  are  employed,  and  the  two  front,  and  the 
three  rear  borders  are  connected  to  separate  regu- 
lators. At  the  opening,  or  front  of  the  reflector  is 
placed  a  wire  screen,  to  protect  the  lamps  and  also 
acts  as  a  fender  in  dropping  or  raising  curtains. 
Each  border  consists  of  one  or  two  separate  cir- 
cuits, and  the  fixture  is  connected  to  the  feeder  by 
means  of  flexible  cables,  the  ends  of  which  termi- 
nate in  connecting  plates  in  the  form  of  a  plug, 
which  corresponds  with  a  receptacle  in  the  con- 
necting block,  to  which  the  wires  from  the  switch- 
board are  connected.  Where  two  circuits  are 
required,  the  lamps  are  connected  alternately. 

74.  Bunch  and  entrance  lights  are  used  for  light- 
ing the  entrance,  or  for  lighting  a  particular  part 
of  the  stage,  when  the  remainder  of  it  is  in  dark- 
ness, etc.,  and  also  for  general  illumination. 

The  bunch  lamps  are  usually  placed  on  an  iron 
fixture,  arranged  so  that  they  can  be  raised  or 
lowered  or  turned  in  any  direction.  The  entrance 
lights  are  usually  lamps  placed  on  a  strip  of  wood 
in  the  shape  of  a  row  of  lights.  The  connections  to 
the  circuit  are  similar  to  those  of  the  border  lights, 


HOW   TO   WIRE   BUILDINGS.  91 

a  receptacle  for  connections  in  the  floor  being 
provided  on  each  side  of  the  stage  and  at  each 
entrance.  These  pockets  or  floor  receptacles  must 
be  fitted  in  such  manner  that  moisture  is  excluded, 
and  constructed  of  fire-resisting  material. 

The  circuit  from  the  switchboard  is  located  on 
the  ceiling  under  the  stage,  and  is  not  connected 
to  a  regulator. 

-75.  Ground  lights  or  rows,  are  constructed  in  a 
manner  similar  to  the  entrance  rows,  and  are  used 
for  illuminating  the  back  of  hedges,  water-falls, 
platforms,  balconies,  etc.,  in  the  scenery,  and  are 
laid  upon  the  floor  of  the  stage,  at  the  point  to  be 
illuminated.  The  receptacles  used  for  the  bunch 
lights  are  made  use  of  for  these.  All  the  stage 
fixtures  are  portable,  and  the  arrangements  for 
connecting  and  disconnecting  must  admit  of  being 
quickly  accomplished. 

76.  Projection  lights  are  used  for  special  pur- 
poses, such  as  throwing  a  beam  of  light  in  the 
shape  of  a  streak  of  lightning  across  the  stage,  or 
directing  it  on  a  person,  or  object,  or  to  suggest 
moving  water,  etc.  The  projection  light  consists  of 
an  arc  light  and  suitable  resistances,  and  is  specially 
designed  for  this  class  of  work.  The  wires  from 
same  can  be  connected  with  the  incandescent  wiring 


92  HOW   TO   WIRE   BUILDINGS. 

system  used  in  the  theatre.  The  lamp  is  provided 
with  screens,  lens,  light  filters,  etc.,  and  special 
appurtenances  for  lightning  effects.  The  fixture  is 
portable  and  the  reflecting  portion  is  arranged  so 
that  it  can  be  turned  in  any  direction,  or  raised  or 
lowered.  The  flexible  cable,  used  for  connecting 
the  lamp  with  the  system,  is  similar  to  that  used 
for  border  and  bunch  lights.  The  connections  and 
locations  are  temporary,  as  the  lamp  is  carried 
from  one  point  to  another  according  to  its  uses. 

There  is,  however,  a  permanent  line  or  circuit, 
carried  from  the  stage  switchboard  to  a  connecting 
block,  located  in  the  front  of  the  gallery.  A  pro- 
jecting lamp  is  used  at  this  point  to  throw  light  of 
different  colors  on  the  ballet,  or  other  quickly 
moving  objects  on  the  stage. 

77.  In  addition  to  the  lights  mentioned,  others 
of  a  temporary  character,  are  used  for  special  pur- 
poses, such  as  chandeliers,  newel  posts,  candelabra, 
hearth,  moon,  sun,  etc.  The  fixtures  for  the  first 
three  are  constructed  of  wood.  The  hearth  lights 
represent  a  fire  in  the  grate,  etc.,  and  are  usually 
ordinary  white  glass  lamps,  placed  in  a  receptacle 
representing  a  grate,  and  the  grate  is  covered  with 
red  paper  or  mica.  The  fixture  which  represents 
the  moon  or  sun,  is  constructed  ordinarily  of  wood, 
in  cylindrical  form,  a  circuit  of  red  and  a  circuit  of 


HOW   TO   WIRE   BUILDINGS.  93 

ordinary  lamps  are  placed  therein,  and  the  face  of 
the  cylinder  is  generally  of  tinted  glass,  sometimes 
formed  and  marked  to  represent  the  object.  Each 
circuit  is  connected  with  a  toning  device,  so  that 
any  tint  may  be  obtained.  By  the  use  of  the  ton- 
ing device,  representations  of  setting  sun  or  rising 
moon  will  be  faithfully  borne  out.  The  lamps  must 
be  located  at  a  distance  from  the  face  or  glass,  so 
that  spots  of  light  or  the  shape  of  the  carbon  will 
not  show. 

Nearly  all  the  materials  used  on  the  stage  for 
theatrical  purposes  are  flimsy  and  highly  inflam- 
mable, and  the  conditions  are  such,  that  a  fire  once 
started  will  gain  rapid  headway.  The  work  of  the 
stage  hands  in  setting  scenes,  etc.,  is  done  in  a 
hasty  manner.  It  is  therefore  necessary  to  provide 
materials  and  to  locate  them  in  such  a  manner  that 
they  will  withstand  the  existing  conditions  ;  and 
care  should  be  taken  in  fastening  permanent  cir- 
cuits, that  they  are  not  on  temporary  structures, 
liable  to  change. 

The  switchboard  should  be  constructed,  as  far  as 
possible,  of  fire-proof  materials,  and  the  whole 
should  have  a  covering  similar  to  the  flexible  roller 
top  used  on  desks,  lined  with  asbestos,  etc. ,  so  that 
when  the  switchboard  is  not  in  service,  it  prevents 
interference  with  appliances,  and  also  acts  as  a 


94  HOW   TO    WIRE   BUILDINGS. 

safeguard  against  falling  objects,  water,  etc.  The 
switches,  cut-outs  and  regulators  should  be  pro- 
vided with  a  suitable  name  plate,  and  be  so  located 
on  the  board  that  connections  with  the  lamp  cir- 
cuits can  easily  be  made  to  provide  for  the  various 
combinations  necessary  in  this  class  of  work.  At 
the  top  of  the  board  should  be  placed  a  pilot  lamp, 
from  each  circuit,  to  act  as  a  guide  for  lighting  or 
toning  purposes. 


HOW   TO    WIKE   BUILDINGS.  95 


CHAPTER  XVII. 


PLANS  OF  DISTRIBUTION. 

78.  All  circuits  should  be  so  distributed  and  con- 
nected throughout  a  structure  that  practically  the 
pressure  or  difference  of  potential  will  be  the  same. 
It  is  often  the  case  that  the  total  amount  of  loss  is 
small,  but  incorrectly  divided  ;  that  is,  the  greater 
part  is  allowed  in  the  lamp  circuit  or  sub-feeder, 
when  it  ought  to  have  been  allowed  in  the  mains  or 
feeder,  or  vice  versa. 

Assuming  5  per  cent,  to  be  allowed  in  the  con- 
ductors, it  is  generally  best  to  distribute  the  loss  as 
follows  :  1  per  cent,  in  the  lamp  circuit,  1|  per  cent, 
in  the  mains,  and  2i  per  cent,  in  the  feeders. 

The  chance  of  having  all  the  lamps  on  any  one 
lamp  circuit  in  use  is  greater  than  the  chance  of 
having  all  the  lamps  connected  to  a  main  in  use ; 
and  a  small  loss  in  the  lamp  circuit,  will  allow  of 
placing  a  few  additional  lamps  on  those  circuits 
without  appreciably  affecting  the  whole  wiring 
system.  The  method  of  distribution  is  governed 
by  the  manner  in  which  the  lamps  are  to  be  used. 
In  some  instances,  the  lights  are  in  use  continuously; 


96  HOW   TO   WIRE   BUILDINGS, 

in  others  a  certain  proportion  are  in  use  at  any 
one  time,  and  in  still  others,  certain  sections  are 
used  at  stated  times.  The  distribution  is  therefore 
guided  by  these  conditions.  The  best  results  are 
secured  when  a  separate  feeder  is  provided,  for  the 
separate  sections  having  different  conditions  of 
lighting. 

79.  All  diagrams  given  here  will  show  only  one 
wire,  unless  otherwise  mentioned,  and  may  be  used 
for  the  2  or  3  wire  system. 

Fig.  1  represents  a  cut-out  box,  either  in  a  panel 
or  closet  located  in  the  centre  of  its  lighting  area, 
and  shows  the  connection  therewith  of  the  floor 
mains,  which  are  connected  with  the  vertical  mains. 

Fig.  2  represents  a  main  and  feeder,  and  more 
particularly  the  various  methods  of  distributing 
from  the  mains  to  the  different  ramifying  points  or 
panels.  A  represents  the  feeder  from  the  switch- 
board in  the  dynamo  room,  connecting  with  the 
mains  B  at  the  point  X,  which  is,  in  this  case,  the 
main  central  point  of  lighting  ;  and  the  lamps  are 
figured  as  being  at  a  distance  equal  to  that  between 
the  switchboard  and  X.  ^'and  D  represent  the 
vertical  mains,  and  if  the  lights  are  evenly  divided 
on  each  floor,  the  distance  is  equal  to  one-quarter 
the  total  length,  B  and  D  connect  with  floor  mains 
at  each  floor.  On  the  4th  floor  M  and  M  represent 


HOW   TO   WIRE  BUILDINGS. 


97 


I 


i- 


a 


98  HOW   TO   WIRE   BUILDINGS. 

the  floor  mains  connecting  with,  the  cut-outs  of  the 
lamp  circuits.  On  the  3d  floor,  to  equalize  the 
pressure,  on  account  of  two  distributing  points,  the 
floor  mains  are  again  divided,  as  shown.  On  the 
second  floor  $  and  Sl  each  represent  a  floor  main, 
and  are  necessary  to  equalize  the  pressure  on  ac- 
count of  the  difference  in  the  number  of  lights  at 
each  box,  and  the  distance,  the  box  yl  being  quite 
close  to  the  feeding  point. 

On  the  1st  floor  is  shown  a  method  which  should 
be  avoided,  because  it  is  impossible  to  equalize  the 
pressure.  If  the  pressure  at  the  lamps  from  box  y* 
is  normal,  the  pressure  at  the  lamps  from  box  y 
and  yl  would  be  above  normal,  and,  on  the  other 
hand,  if  the  pressure  at  the  lamps  from  y  is  normal 
that  at  the  lamps  from  box  y1  and  yz  would  be 
below  normal.  We  therefore  have  a  choice  of  two 
evils,  running  the  majority  of  lamps  below  their 
rated  candle-power,  or,  increasing  the  pressure,  and 
lamp  breakage. 

Fig.  3  represents  a  main  and  feeder  system  some- 
what similar  to  that  shown  in  Fig.  2,  except  that 
the  floors  are  greater  in  number.  F  represents  the 
main  feeder,  connecting  with  the  sub-feeders  Fl  and 
F*  at  the  point  A.  Fl  and  F*  extend  from  A,  and 
connect  with  the  main  feeders  c  at  the  points  D 
and  E.  M  represents  the  floor  mains  connecting 


HOW   TO    WIRE  BUILDINGS. 


99 


yj       y* 


Y*       Y'        Y 


.  2. — PLANS  OF  DISTRIBUTION. 


100  HOW    TO    WIRE   BUILDINGS. 

with  the  lamp  circuits.  In  large  buildings  the 
feeder  systems,  as  shown  in  Figs.  2  and  3,  can  be 
provided,  for  each  side  of  the  building. 

Fig.  4  represents  a  plan  of  floor  lighting,  used  in 
factory  or  general  exposed  work.  A  represents  the 
main  feeder,  connecting  with  the  sub-feeders  B  and 
Bl\  at  the  point  Y  the  sub-feeders  connect  with 
the  main  wires  C  and  C1  at  the  point  X,  which  in 
turn  connects  with  the  lamp  circuits  L.  Fig.  5, 
represents  a  system  of  distribution  somewhat 
similar  to  that  shown  in  Fig.  4.  In  Fig.  5  the 
wires  forming  both  sides  of  the  circuits  are 
shown.  This  method  is  made  use  of  where  all  the 
lights  on  any  circuit  are  used  at  the  same  time,  and 
are  turned  on  or  off  by  means  of  switches.  This 
method  can  be  applied  when  lighting  large  spaces, 
such  as  sheds,  depots,  etc.  A  represents  a  main 
feeder  forming  one  side  of  the  circuit,  and  its  car- 
rying capacity  is  computed  at  the  total  number  of 
lights,  and  connects  at  B  with  A  A,  which  is  the 
main  wire  forming  one  side  of  the  circuit  and  con- 
nects with  the  wire  forming  that  side  of  the  lamp 
circuit  on  each  circuit  at  the  point  E.  S  and  Sl 
represent  the  wires  forming  each  side  of  the  lamp 
circuit.  C1  C*  C3  C*  are  divisional  mains  forming 
one  side  of  the  feeder  circuit  and  connecting  with 
&  Sit  the  points  K.  It  will  be  seen  that  the  feeder 


HOW   TO    WIRE  BUILDINGS. 

M     .      M 


101 


FIG.  3. — PLANS  OF  DISTRIBUTION. 


102  HOW   TO   WIRE   BUILDINGS. 


X 


B> 


&•••• 


X 


FIG.  4. — PLANS  OF  DISTRIBUTION. 


HOW   TO   WIRE  BUILDINGS  103 

A,  and  mains  AA  and  the  lamp  wires  S,  form  one 
side  of  the  entire  circuit,  A  and  A  A  being  common 
carriers  to  all.  On  the  other  side  of  the  circuit  Sl 
forms  one  side  of  each  lamp  circuit  independent  of 
each  other,  and  the  feeders  marked  C1  Gl  C3  C*  are 
connected  to  Sl  and  also  independent  of  each  other. 
At  the  terminals  of  the  feeders  are  placed  single 
pole  switches,  by  means  of  which  any  of  the  cir- 
cuits can  be  connected  without  affecting  the  other. 

Fig.  6  represents  a  system  somewhat  similar 
to  that  shown  in  Fig.  5,  except  that  in  Fig.  5 
the  feeders  were  connected  at  the  centre  of  the 
length  of  the  mains.  In  this  case,  sub-feeders 
are  necessary,  due  to  increased  length,  so  that  the 
pressure  at  the  point  X  in  the  mains  would  equal 
that  at  the  point  T.  The  method  of  connecting 
the  lamps,  or  throwing  them  in  or  out  of  circuit, 
is  the  same  as  explained  in  Fig.  5. 

Fig.  7  is  somewhat  similar  to  Figs.  4  and  5, 
except  in  this  case  two  separate  feeders  are  pro- 
vided for  the  purpose  of  equalizing  the  pressure, 
and  forming  two  separate  circuits  of  each  row  of 
lamps,  each  circuit  being  independent  of 'the  other, 
on  the  same  row,  and  also  of  those  on  the  other 
row.  One  side  •  of  the  lamp  circuit  wire  is  dis- 
connected at  the  middle,  and  each  half  is  fed  or 
connected  to  a  separate  divisional  feeder.  The 


104  HOW  TO  WIRE  BUILDINGS. 


c* 


5 

S'        S 

S*        S 

^/          ^ 

S* 

S 

E   AA     , 

E   B      f 

/-^r^r    ,, 

>fi 

^"""^~l 

"T 

/ 

X 

X 

X 

A 

S 

S' 

s 

S* 

5 

5/ 

5 

S' 

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v 

/* 

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A 

J~~                       ~^ 

A          1 
A1, 

4.**?* 

FIG.  5. — PLANS  OF  DISTRIBUTION. 


HOW   TO   WIRE  BUILDINGS. 


105 


C* 


E 


E . 


C+&C* 

FIG  6. — PLANS  OF  DISTRIBUTION. 


106  HOW   TO   WIRE   BUILDINGS. 

method  of  throwing  in  or  out  of  circuit  by  switches 
is  similar  to  that  as  described  in  Fig.  4. 

Fig.  8  represents  a  system  of  distribution  ap- 
plicable to  large  isolated  plants,  and  by  a  few 
alterations  in  the  method  can  be  used  for  central 
station  distribution.  (The  diagram  shows  a  "flat" 
plan).  In  large  hotels  the  lighting  conditions  are 
constantly  varying  ;  that  is,  all  the  lights  in  one 
section  of  the  building  may  be  in  use  at  one  time, 
and  most  of  those  connected  on  the  feeders  in  the 
other  sections  not  in  use,  and  vice  versa.  Conse- 
quently the  pressure  on  the  wires  is  undergoing 
variations  constantly,  the  result  of  which  would  be 
excessive  lamp  breakage,  unsatisfactory  service, 
etc.  Under  certain  conditions  it  is  not  practical  to 
wire  at  a  low  rate  of  loss,  on  account  of  the  im- 
mense increase  in  first  cost.  The  interest  on  the 
investment  will  more  than  offset  the  small  addi- 
tional cost  of  pressure  equalizers  and  the  lost 
energy  in  same. 

Therefore,  when  the  conditions  exist  as  stated, 
the  conductors  are  installed  at  a  higher  rate  of  loss. 
In  the  diagram,  Fl  to  F*  represent  the  vertical 
feeders,  connecting  to  the  mains  and  floor  mains, 
in  the  different  sections  of  the  building.  The  dia- 
gram also  shows  the  different  methods  of  feeding, 
which  can  be  employed  in  each  section.  K  repre- 


HOW   TO   WIRE  BUILDINGS.  107 


FIG.  7. — PLANS  OF  DISTRIBUTION. 


108  HOW   TO    WIRE   BUILDINGS. 

sents  a  ' '  crib ' '  to  which,  all  the  different,  sectional 
feeders  connect.  E  to  E*  represent  main  feeders 
connecting  to  the  "crib"  and  extending  to  the 
dynamo  switchboard.  On  the  wire  forming  one 
side  of  each  is  connected  a  pressure  equalizer,  con- 
necting with  the  crib  at  the  point  where  the  main 
feeders  connect ;  and,  extended  to  the  dynamo 
room  switchboard,  are  run  a  pair  of  wires  for  each 
feeder,  which  are  connecting  with  a  pressure  indi- 
cator. As  the  pressure  varies  at  any  of  the  feeder 
points  on  the  "  crib,"  gthe  same  will  be  indicated  on 
the  instrument  and  by  throwing  coils  of  the  equal- 
izer, out  or  in,  the  pressure  can  be  maintained  at  a 
certain  point. 

Fig.  9  shows  the  method  of  connection,  at 
the  switchboard,  with  the  dynamo  and  feeders. 
A  and  A  A  represent  "Bus."  wires  which  act  as  the 
main  or  trunk  line.  Connected  to  this,  are  the 
different  main  feeders,  and  the  leads  from  the 
dynamos.  A  pressure  indicator  is  connected  with 
the  "Bus."  lines,  to  indicate  the  pressure  in  that 
part  of  the  wiring  installation.  On  the  positiv^ 
dynamo  lead  is  placed  an  ampere-meter. 

The  negative  wires  of  the  feeder  circuits  are  con- 
nected to  the  "Bus."  bar  A.  The  positive  feeder 
wire  terminates  and  connects  to  the  f aceboard  of 
the  equalizer,  and  from  another  connection  on  the 


HOW   TO   WIRE   BUILDINGS.  109 


V  «• 

I 


•M 

\ 


FIG.  8. — PLANS  OF  DISTRIBUTION. 


110 


HOW    TO   WIRE  BUILDINGS. 


*  39* 


cc 


HOW   TO   WIRE  BUILDINGS. 


Ill 


equalizer  faceboard ;  and  connecting  with.  A  A  of 
the  "  Bus."  bar,  is  run  another  wire,  equal  in  cross- 
section  to  that  of  the  feeder.  The  equalizer  and 
pressure  indicator  of  each  feeder  circuit  should  be 
placed  directly  over  each  other,  so  that  when 
throwing  coils  in  or  out  of  the  circuit,  the  effect 
can  be  noticed.  It  will  also  tend  to  simplify  mat- 
ters. 


/1/W1/1 


AWW4WW 


MM/V 


FIG.  10.— PLANS  OF  DISTRIBUTION. 

Fig.  10  represents  the  coils  and  method  of  con- 
nections, in  the  equalizer,  and  to  the  feeder,  and 
"Bus"  bar  or  wires  on  the  dynamo  switchboard. 


112  HOW    TO    WIRE   BUILDINGS. 

Assuming  each,  coil  to  have  a  resistance  of  1  ohm, 
and  that  there  were  10  coils,  it  will,  from  the  con- 
nections, readily  be  seen  how  the  resistance  can  be 
varied. 


HOW    TO    WIRE   BUILDINGS.  113 


CHAPTER    XYin. 


DISTRIBUTION  OF  LIGHT. 

80.  In  locating  lamps,  they  should  be  so  dis- 
tributed, that  each  lamp  performs  its  equal  share 
of  the  lighting,  and  is  so  located  that,  if  the 
candle  power  of  each  lamp  is  the  same,  the 
diffusion  of  light  will  be  equal,  and  if  the  number 
of  lamps  is  sufficient,  a  space  can  be  illuminated 
in  such  manner  that  the  light  is  practically  equal 
throughout. 

The  number  of  lamps  is  governed  by  the  space 
to  be  lighted,  the  purpose  for  which  the  structure 
is  used,  etc. 

The  practical  unit  of  light  is  the  16  candle-power 
lamp,  and  for  ordinary  illumination,  one  16  candle- 
power  lamp  for  every  100  square  feet,  suspended 
about  8  feet  from  the  floor,  is  allowed.  By  100 
square  feet  is  meant  a  space  10  ft.  x  10  ft.,  or 
8  ft.  x  12  ft.,  etc.  The  amount  of  light,  on  this 
basis,  is  allowed  only  when  the  conditions  are  such 
that  ordinary  illumination  is  required,  as  in  sheds, 
depots,  walks,  etc.,  and  where  close  inspection  of 
materials,  etc.,  is  not  necessary.  In  waiting-rooms, 


114 


HOAV    TO    WIRE   BUILDINGS. 


ferry  houses,  etc.,  the  allowance  is  generally  one 
16  candle-power  lamp  to  every  75  square  feet.  In 
stores,  offices,  etc.,  for  ordinary  lighting  purposes, 
60  square  feet  is  the  usual  allowance. 

81.  Fig.  1  represents  the  ideal  method  of  dis- 
tribution, but  in  practice  is  objectionable,  where 
pendants  from  the  ceiling  are  used>  When  the 
lamps  are  located  close  to  the  ceiling  and  a  'fixture 


JO          JO' 


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FIG.  1. — DISTRIBUTION  OF  LIGHT. 

or  finish,  corresponding  to  the  surroundings,  is 
made,  the  effect  is  very  good.  In  the  diagram, 
assuming  the  space  to  be  lighted  is  50  ft.  x  50  ft, 


HOW    TO    WIRE   BUILDINGS. 


115 


and  the  candle-power  of  the  lamp  is  16,  to  find  the 
number  of  lamps  necessary,  50x50  =  2500  ft  -*- 100  = 
25 — 16  candle-power  lamps.  Dividing  the  ceiling  in 
squares  of  100  ft.  or  10  x  10  and  placing  a  lamp  in 
the  centre  of  the  square,  each  light  will  have  the 
same  amount  of  space  to  light,  and  the  lamps  will 
be  an  equal  distance  from  each  other. 

If  in  the  same  space,  it  is  intended  to  place  two 
lamps  in  a  cluster,  to  obtain  an  even  diffusion  it  is 


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/'           xv 

/                     N\ 

/                     \ 

x'X 

x'                              \ 

x                         N> 

FIG.  2.— DISTRIBUTION  OF  LIGHT. 

necessary  to  use  32  lamps  instead  of  25  as  in  the 
first  case. 


116 


HOW  TO   WIRE  BUILDINGS. 


Fig.  3  shows  a  method  of  distribution,  each  out- 
let having  a  cluster  of  four  lamps  instead  of  single 
lamps. 


Iff  8 


IG'S 


06 


\                         s 

"\                                      / 

\            ^\              ' 

XN                            /' 

^                                 / 

X                 '^                X 

\                   / 

\                     / 

v-       ^0*      s 

\             / 

\                S 

v      ^f    x 

:*-: 

X 

/?  ^4f  x/  jx    ^  iiX  f/ 

s          x 

X             x 

f                 \ 

xX 

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/'                          X 

x                         x 
/ 

x''           ^          ^x, 

/ 

X                                                      / 

\                             xx 

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v                          / 

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X                         X 

\                   ' 

x                ,^ 

\            / 

\.           , 

\                  X 

K 

>: 

f     v 

/          s 

s         ^ 

X                         S 

/                            N 
X                                      X 

/                         v 

x                                   \ 

\ 

x                                     x 

/                                      x 

xx                               x 

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N                                           X 

x                                  / 

\                    / 

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\                  / 

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^             s 

w 

# 

& 

x    '      x 

X              X 

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X                         X 

/                 ^ 

X                       N 

X                                 x 

/                       N 

x                     XK 

X                                        X 

/                            \ 

/                                       - 

/'                                \ 

/                                           *l 

FIG.  3.  —  DISTRIBUTION  OF  LIGHT. 


Dividing  the  lamps  into  clusters,  requires  more 
lamps  for  the  same  space,  and  the  greater  the 
number  of  lights  at  any  one  point,  the  more  uneven 
will  the  lighting  effect  be. 

82.  Lighting  from  the  side  wall  is  not  as  econom- 
ical as  from  the  ceiling,  and  the  results  are  limited. 
Ordinarily  side  lights  are  only  used  to  equalize  the 
diffusion  of  light,  when  the  lighting  from  chande- 


HOW    TO    WIRE   BUILDINGS.  117 

Hers,  or  in  a  small  room,  and  where  a  fixture  from 
the  ceiling  will  impart  a  crowded  appearance.  For 
the  same  reason,  it  is  undesirable  to  place  two 
chandeliers  in  the  same  room.  In  still  other  in- 
stances the  chandeliers  would  obstruct  the  view, 
and  the  lights  would  be  in  the  line  of  sight.  The 
best  results,  where  reflectors  are  used,  are  obtained 
by  placing  the  bulb  lengthwise,  or  parallel  with 
the  reflector  ;  and  by  placing  the  lamp  near  to  the 
surface  of  the  reflector,  the  reflecting  power  is  in- 
creased. When  placing  shades  or  globes  over  the 
lamps,  allowance  must  be  made  in  the  amount  of 
light,  as  a  large  quantity  is  absorbed,  according  to 
the  shape,  color,  and  proximity  to  the  lamp.  The 
surrounding,  or  prevailing  color,  of  the  walls,  etc. , 
must  also  be  considered  in  the  location  and  number 
of  lamps.  Where  shadows  are  created,  due  to 
pilasters,  etc.  (where  the  light  is  evenly  diffused 
there  will  be  no  shadows),  to  overcome  the  shadows, 
locate  some  lamps  on  the  side  of  the  pilaster,  on 
which  the  shadow  is  thrown,  or  a  circle  of  lights 
around  the  pilaster.  This  will  remedy  the  defect. 

83.  Lighting  by  electricity,  on  account  of  the 
absence  of  extreme  heat,  admits  more  artistic 
display,  than  does  any  other  artificial  illumination. 
Lamps  can  be  located  in  recesses  in  the  walls  and 
ceilings,  exposing  only  the  lower  half  of  the  lamp 


118  HOW    TO    AVI  RE    BUILDINGS. 

bulb  ;  or,  they  may  be  concealed  entirely  and  for 
their  cover  may  have  a  finely  finished  piece  of 
artistic  glassware,  etc.  They  can  also  be  arranged 
to  form  geometrical  figures,  or  placed  in  the  centre 
of,  or  at  the  intersection  of  the  figures  forming  the 
decorations.  When  placed  in  recesses  and  covered 
by  glass,  the  distance  between  the  lamp  and  glass 
cover  should  be  such,  that  the  shape  of  the  carbon 
or  lamp  is  not  visible  on  or  through  the  glass. 

In  lighting  theatres,  concert  rooms,  lecture  halls 
and  similar  places,  in  which  tnere  is  some  objective 
point,  such  as  a  stage  or  platform,  the  division, 
location  and  quantity  of  light  should  be  such,  that 
the  proper  effect  at  the  objective  point  is  secured, 
and  that  the  light  does  not  strain  the  eyes  of  the 
audience,  and  that  the  line  of  vision  is  not  ob- 
structed by  light  between  the  objective  point,  and 
the  audience.  The  lights  should  be  so  arranged 
that  there  is  no  reflection  in  the  eyes.  They  should 
be  located  at  the  back  of,  or  considerably  above, 
the  audience. 

When  lighting  show  windows  in  stores,  etc., 
locate  the  lamps  as  nearly  as  possible  in  the  corner 
where  the  front  intersects  with  the  ceiling,  pro- 
viding a  tin  shade  or  reflector  having  a  white 
surface,  and  extending  the  same  the  entire  length 
of  the  front,  and  placing  the  flat  of  the  lamps 


HOW   TO    WIRE   BUILDINGS.  119 

parallel  with,  the  reflector,  and  quite  close  to  it. 
The  sidewalk  should  be  darkened  as  much  as 
possible  to  obtain  good  results. 

To  illuminate  stained  and  cathedral  glass  win- 
dows or  ordinary-sized  windows,  form  a  reflector 
on  each  side  of  the  window  to  be  lighted,  and  place 
therein  a  sufficient  number  of  lamps,  so  that  a 
strong  light  will  be  obtained,  and  locate  the  same 
at  a  distance  from  the  windows,  so  that  the 
diffusion  of  light  will  be  equal,  and  that  the  spots 
of  light,  or  the  carbons  of  the  lamps,  will  not  be 
discernible.  Increase  the  dimensions  of  the  win- 
dow, and  the  number  of  lamps  and  distance 
between  same  and  the  window,  must  be  increased. 

84.  One  of  the  most  difficult  problems,  in  the  art 
of  lighting  is  the  illumination  of  large  paintings, 
etc.  In  fact,  each  subject  is  a  separate  problem, 
and  must  be  treated  accordingly.  The  treatment 
changes  according  to  the  size,  shape,  prevailing 
colors,  if  covered  with  glass  or  not,  and  the  sur- 
roundings. The  usual  method  is  to  place  the  lamps 
in  a  reflector,  which  is  as  long  as  the  width  of  the 
picture,  the  reflector  is  shaped  according  to  the 
size  of  the  picture  and  the  number  of  lights  and  dis- 
tance between  the  reflector  and  picture  to  be  lighted 
must  be  such  that  the  light  is  evenly  diffused  over 
the  whole  surface,  and  in  such  a  manner  that  the 


120  HOW    TO    AVIRE   BUILDINGS. 

picture  can  be.  viewed  equally  as  well  from  either 
side,  and  so  that  the  view  will  not  be  impaired  by 
counter-reflection. 

If  the  painting  is  suspended  from  or  fastened  to 
the  side  wall,  there  should  be  no  side  lights  located 
in  its  near  vicinity  ;  and  if  placed  on  a  stand 
or  easel  in  the  centre  of  the  floor,  care  should  be 
taken  not  to  have  any  lights  at  the  back  of  the 
painting,  which  tends  to  counteract  the  effect  when 
viewing  the  picture. 

Paintings  placed  in  a  wooden  box  and  covered 
with  glass,  are  the  most  difficult  of  all,  as  the  sur- 
rounding objects  will  be  reflected  in  the  glass.  To 
overcome  this  requires  an  abundance  of  light,  and 
the  best  results  can  only  be  decided  by  actual  ex- 
periment. 

It  is  impossible  to  define  rules  governing  all  con- 
ditions of  lighting.  The  object  of  this  chapter  has 
been  to  describe,  in  a  general  way,  the  methods 
usually  employed,  and  the  amount  of  light  neces- 
sary for  general  illumination,  and  to  suggest  the 
method  usually  preferable  in  special  cases.  The 
style  and  methods  to  be  employed  can  only  be 
decided  by  experience. 


HOW   TO   WIRE   BUILDINGS.  121 


CHAPTER    XIX. 

DISTRIBUTION  OF  LABOR  AND  HINTS  TO  FOREMEN. 

85.  The  amount  of  labor  is  governed  by  most  of 
the  conditions,  as  stated  in  previous  chapters,  but 
it  can  be  so  divided  and  directed,  that  the  best 
results  will  be  obtained,  from  an  executive  and 
financial  standpoint. 

Let  us  assume  a  case  in  which  the  plans  have 
been  drawn  in  the  drafting-room  of  the  electric 
lighting  company,  and  turned  over  to  the  foreman 
in  charge,  with  instructions  to  install  the  work. 
Let  us  also  assume  (which  is  very  often  the  case", 
that  the  draftsman  had  not  seen  the  building.  The 
foreman,  from  these  plans,  estimates  the  amount  of 
material  required,  and  after  ordering  same,  he 
should  familiarize  himself  with  the  structure  ;  ob- 
serve which  portions  of  the  building  are  in  a  more 
advanced  state  of  construction,  and  the  manner  in 
which  the  labor  in  the  various  branches  of  the 
building  trades,  is  distributed. 

The  plans  instruct  him  as  to  the  general  location 
of  wires,  and  the  distribution  of  current,  but  he  is 
responsible  for  the  mechanical  details,  and  waste 


122  HOW    TO    WIRE   BUILDINGS. 

(if  any)  of  labor.  Before  the  materials  are  received, 
he  should  select  a  safe  place  for  same,  and  arrange 
to  keep  the  i '  lockup  ' '  locked. 

When  acquainted  with  the  conditions  of  the 
building,  he  decides  upon  the  number  of  men,  that 
can  be,  to  good  advantage,  employed  on  the  work 
at  any  one  time.  The  work  should  be  started  in 
that  portion  of  the  building,  which  is  in  a  more 
advanced  state  of  construction,  so  that,  when  once 
started,  it  can  be  completed  without  interruption 
or  delay.  It  is  advisable  to  keep  the  same  men  in 
the  same  part  on  the  different  floors  of  the  build- 
ing, so  that  they  will  become  familiar  with  the 
circuits  in  that  section,  as  nearly  all  the  office 
buildings,  etc.,  from  the  second  floor  up,  are  the 
same.  This  will  enable  the  man,  after  completing 
one  floor,  to  do  the  work  more  quickly  on  each 
succeeding  floor.  It  also  demonstrates  whether  the 
amount  of  work  is  satisfactory,  and  when  testing 
the  result  will  show  whether  the  man  is  careful  or 
not.  It  is  to  the  foreman's  interest  to  acquaint 
himself  with  the  capabilities  of  the  men  under  his 
supervision,  so  that  he  is  better  enabled  to  decide 
which  to  place  on  the  more  exacting  and  difficult 
work.  The  lengths  of  the  circuits  as  shown  on  the 
plan  should  be  conformed  with,  as  nearly  as  possi- 
ble. The  exact  sizes  of  wires  as  noted  on  the  plan 


HOW    TO    WIRE   BUILDINGS.  123 

should  be  used  in  all  cases,  but,  should  it  become 
necessary  to  change  the  work,  from  the  "  lay-out'' 
on  the  plan,  the  company  should  be  notified  in 
season,  so  that  instructions  regarding  the  change 
may  be  given,  and  that  the  work  will  not  be 
delayed,  waiting  for  instructions. 

86.  When  the  top  or  lamp  circuits  are  nearly 
completed,  provision  should  be  made  for  testing 
them.  It  is  also  time  to  arrange  for  the  cut-out 
boards  which  are  to  be  set  in  the  panel  or  closet. 
About  this  time,  also,  the  question  of  running  the 
mains  and  feeders  should  demand  attention. 

The  foreman  should  continually  stroll  through 
the  building,  watching  the  work  already  completed; 
the  work  under  way  ;  observing  the  advancement 
in  construction  of  the  different  portions  of  the 
building,  and  continually  calculating  as  to  the 
method  of  procedure  on  his  own  task,  so  that  the 
wiring  work  will  not  delay  the  work  in  other 
branches,  or  vice  versa. 

One  familiar  with  the  method  of  testing  should 
be  appointed  to  do  this  work,  and  his  duty  should 
not  only  be  to  test,  but  he  should  locate  and  repair 
faults,  and  "pick-up"  and  finish  the  innumerable 
"odds  and  ends"  which  were  left  undone.  One 
of  the  most  important  labor-saving  methods,  is  to 
' '  lay-out ' '  and  Work  all  the  circuits,  which  run 


124  HOW   TO    WIRE   BUILDINGS. 

parallel  to  each  other,  at  the  same  time,  all  of 
which  connect  to  different  cut-outs  in  the  same  box. 
It  will  obviate  crosses,  and  to  a  great  extent  sim- 
plify matters.  It  is  easier  to  trace  the  different 
circuits. 

The  same  plan  is  suggested  when  wires  pass 
through  walls,  etc.,  provision  can  be  made,  at  one 
time,  for  all.  The  most  experienced  and  careful 
men  should  construct  the  cut-out  and  switchboards, 
and  run  the  mains  and  feeder. 

87.  The  foreman  should  provide  himself  with  a 
note-book,  he  will  find  it  to  be  of  service  both  to 
himself  and  employer.  He  should  keep  a  record 
of,  the  date,  amount,  and  kind  of  material ;  the 
result  of  each  test ;  the  changes  (if  any)  in  the 
wiring ;  additions  or  omissions  in  the  lamps, 
switches,  etc.,  the  cause  thereof  ;  extra  work  (if 
any)  and  by  whose  authority  ;  the  general  condi- 
tion of  the  plant  when  turned  over  to  the  customer; 
whether  dynamo  is  belted  direct  to  engine  ;  if  so, 
whether  engine  does  other  work  besides  driving 
dynamo.  If  belted  to  pulley  countershaft,  note 
variations  of  speed,  if  any,  and  such  other  data  as 
may  be  of  interest  to  his  employer,  and  obviate 
trouble  for  the  future  consumer. 


HOW   TO    WIRE   BUILDINGS.  125 


CHAPTER    XX. 


PRELIMINARY  TO  RULES,  ELECTRICAL  DATA,  ETC. 

88.  -f  is  the  sign  of  addition,  and  is  called  plus. 
Thus  2  -f  6  indicates  that  6  is  to  be  added  to  2  and 
is  read  2  plus  6  or  A  -f  B,  etc. 

-  is  the  sign  of  subtraction,  and  is  called  minus. 
Thus  6  —  2  indicates  that  2  is  to  be  subtracted  from 
6,  and  is  read,  6  minus  2  or  b  —  a,  etc. 

X  is  the  sign  of  multiplication,  and  is  read, 
times,  or  multiplied  by.  Thus  2x6  indicates  that 
2  is  to  be  multiplied  by  6,  and  is  read  6  times  2, 
and,  a  x  b  denotes  that  multiplication  of  a  x  b. 

•*•  is  the  sign  of  division,  and  is  read,  divided  by. 
Thus  6  -*-  2  is  an  indication  that  6  is  to  be  divided 
by  2. 

Division  is  also  indicated  by  writing  the  dividend 

above  and  the  divisor  below  a  short  horizontal  line 

n 

as  in  a  fraction,  thus  -^  The  exponent  of  a  quan- 
tity is  the  number  which  indicates  how  often  the 
quantity  is  used  as  a  factor.  Thus,  A3  indicates 
that  A  is  to  be  used  as  a  factor  three  times,  and  A3 
is  the  same  as  A  x  A  x  A. 


126  HOW   TO    WIRE    BUILDINGS. 

A8  is  read,  "  A  square"  or  "A  second  power," 
A3  is  read  "  A  cube  "  or  "  A  third  power,"  and,  if 
A  =  6,  A'  =  6  x  6  =  36,  or  A3  =  6  x  6  X  6  or 
6X6  =  36X6  =  A  =  218. 

The  co-efficient  is  a  number  written  before  a 
quantity  to  show  how  many  times  the  quantity  is 
to  be  taken.  Thus  3A  would  show  that  A  is  to  be 
taken  three  times,  and  if  A  —  6,  3A  =  6  x  3  = 
3A  =  18. 

An  algebraic  expression,  is  the  expression  of  a 
quantity,  by  means  of  algebraic  symbols  ;  the 
symbols  indicate  the  relation  of  quantities. 

A  formula  is  a  method  of  expressing  in  a  simple 
and  concise  form,  a  rule  or  principle,  and  show  the 
relation  of  one  to  another.  Yolt  is  the  unit  of 
electrical  pressure,  (electromotive  force)  and  is 
represented  by  E. 

Ampere  is  that  current  having  an  electric  pres- 
sure of  1  volt  which  flows  through  a  wire  having  a 
resistance  of  one  ohm,  and  is  represented  by  C. 

Ohm  is  that  amount  of  resistance  which,  in  a 
conductor,  would  limit  the  current,  having  a  pres- 
sure of  one  volt,  flowing  through  same,  to  one 
ampere,  and  is  represented  by  R. 

According  to  Ohm's  law,  the  current  in  amperes 
is  equal  to  the  electromotive  force  in  volts  divided 

E 
by  the  resistance  in  ohms,  thus,  C  =   --- 


HOW    TO    WIRE    BUILDINGS.  127 

The  electromotive  force  in  volts  is  equal  to  the 
product  of  the  current  in  amperes,  and  the  resist- 
ance in  ohms.  Thus,  E  =  C  x  R.  The  resistance 
in  ohms  is  equal  to  the  electromotive  force  in  volts 

E 

divided  by  the  current  in  amperes.     Thus  E,  =  ~^- 

From  these,  can  be  ascertained  the  current  in 
amperes,  when  the  electromotive  force  in  volts,  and 
the  resistance  in  ohms  is  known,  and, 

The  electromotive  force  in  volts,  when  the  current 
in  amperes,  and  the  resistance  in  ohms  is  known, 
and, 

The  resistance  in  ohms,  when  the  current  in 
amperes,  and  the  electromotive  force  in  volts  is 
known. 

Therefore  in  a  machine,  the  resistance  of  which 
=  .5  ohm  and  the  electromotive  force  in  volts  = 

E  =  100  volts 
100,  the  current  in  amperes  equals    -p  _   ~ — r- 

C  =  200  amperes,  and,  C  x  R  =  E.     200  amperes 

E  =  100  volts 
=  100  volts,  and,     c  =  200  amperes  = 

=  .5  ohm. 

89.  To  ascertain  the  available  current  in  amperes, 
not  generated  at  the  dynamo,  but  for  consumption 
by  or  in  the  lamps,  the  resistance  of  the  conductors 
must  be  added  to  the  internal  resistance  of  the 


128  HOW    TO    WIKE    BUILDINGS. 

dynamo,    and    if   the    resistance   of    the    conduc- 
tors   equals    .0555     ohm,     the     available     current 

E  =  100  volts  100 

ls'    B  =  .6  ohm  x  B  =  .0555    :  :    .5555  = 
180  amperes. 

To  ascertain  the  combined  resistance  of  a  number 
of  lamps  connected  in  multiple,  divide  the  resist- 
ance of  one  lamp  by  the  number  of  lamps.  Thus, 
the  combined  resistance  of  40  lamps  connected  in 
multiple,  the  resistance  of  one  equaling  200  ohms, 

200  ohms  =  B  of  1  lamp 
W0uldbe  40  lamps  =  5  ohms. 

To  ascertain  the  combined  resistance  of  a  num- 
ber of  lamps  connected  in  series,  multiply  the 
resistance  of  one  lamp,  by  the  number  of  lamps. 
Thus,  the  combined  resistance  of  10  lamps  con- 
nected in  series,  the  resistance  of  one  lamp  equals 
200  ohms,  would  be, 

B  of  1  lamp  x  number  of  lamps.      Total  resistance 
200  X  10  =      2000  ohms. 

To  ascertain  the  combined  resistance  of  a  number 
of  series  of  lamps,  the  series  connected  in  multiple, 
divide  the  resistance  of  one  series  by  the  number 
of  series.  Thus,  the  combined  resistance  of  4  series 
connected  in  multiple,  the  resistance  of  one  series 
equal  2000  ohms,  would  be, 
2000  ohms  =  B  of  1  series 


4  series 


=  500  ohms. 


HOW    TO    AVIRE   BUILDINGS.  129 

Therefore,  to  ascertain  the  resistance  required  in 
the  conductors,  so  that  the  loss  in  same  equals,  in 
the  desired  per  cent.,  a  certain  proportion  of  the 
total  resistance,  it  is  necessary,  if  connected  in 
multiple  or  series,  to  first  ascertain  the  combined 
resistance  of  the  lamps,  and  assuming,  20  lamps 
connected  in  multiple,  the  resistance  of  each  lamp 
being  180  ohms,  5  per  cent,  loss  of  electrical  energy 
to  be  allowed,  in  the  conductors ;  the  distance 
being  350  feet  from  the  dynamo,  therefore, 
B  of  one  lamp  ==  180  ohms  =  g  =  Totalresist  of 
Number  of  lamps  =  all  iampS) 

and,  9  ohms  representing  95  per  cent,  of  the  total 
resistance  of  the  circuit  at  5  per  cent,  loss,  the  total 

resistance  is,  — Q^ =  9,474  ohms  =  total  resist- 
ance of  lamp  circuit.  The  length  of  the  wire 
being  350  X  2  =  700  feet,  and,  .474  ohm  is  the 
resistance  necessary  to  be  contained  in  a  wire  700 
feet  in  length,  to  supply  current  to  20  lamps  located 
at  a  distance  of  350  feet  from  the  dynamo.  If  the 
lamps  are  connected  in  series,  first  ascertain  the 
total  resistance  of  the  series,  and  the  method  of 
ascertaining  the  resistance  of  the  conductor  is  sim- 
ilar to  that,  when  the  lamps  are  connected  in  mul- 
tiple, assuming  the  same  number  of  lamps,  per  cent, 
of  loss  and  distance  from  the  dynamo,  to  be  the 


130  HOW   TO   WIRE   BUILDINGS. 

same  as  in  last  example,  but,  that  the  lamps  will 
be  connected  in  series  instead  of  multiple,  there- 
fore the  combined  resistance  of  all  the  lamps  equals, 
180  —  R  of  one  lamp 
20  —  Number  of  lamps 
3600  =  Total  R  of  all  lamps. 

5  per  cent,  being  the  desired  amount  of  loss  in  the 
conductors,  therefore  3600  ohms  represents  95  per 
cent,  of  the  total  resistance  of  the  lamp  circuit,  and, 

3600  X  100 

Q5       -   =  3789.4  ohms  =  total  R  of  lamp  circuit, 

therefore,  3600  ohms  =  R  of  Lamps  =  95  per  cent. 
of  circuit,  and,  189.4  ohms  =  R  of  conductors  —  5 
per  cent,  of  circuit  resistance. 

90.  To  ascertain  the  resistance  of  a  one  or  a  num- 
ber of  corresponding  wires,  the  method  is  similar 
to  that  for  lamps.  Mil.  =  .001  of  an  inch,  and 
when  made  use  of  in  relation  to  wiring,  is  the  unit 
of  length,  when  measuring  the  diameter,  or  cross - 
section  of  wires.  Circular  Mil  is  the  unit  of  area 
employed  in  measuring  the  areas  of  cross-sections 
of  wire. 

The  diameter  or  cross-section  of  a  wire  is 
expressed  in  mils,  and  the  area  of  cross-section  in 
circular  mils,  therefore  a  wire,  the  diameter  of 
which  equals  i  inch  —  250  mils,  and  to  ascertain 
the  circular  mils  it  is  necessary  "  to  square"  the 


HOW   TO    WIRE   BUILDINGS.  131 

diameter,  d',  250  X  250  =  62500  circular  mils. 
Foot-mil,  equals  a  wire,  the  length  of  which 
equals  one  foot,  and  the  diameter,  one  mil ;  it  is 
used  in  practice  as  a  basis  for  computing  the 
resistance  of  any  given  wire,  and  if  the  copper  is 
commercially  pure  (usually  96  per  cent,  conduc- 
tivity), the  resistance  of  same,  at  75°  Fahrenheit, 
equals  10.79  ohms. 

The  resistance  of  a  copper  wire  is  equal  to  its 
length  in  feet,  multiplied  by  the  resistance  of  one 
foot-mil,  10.79,  and  divided  by  the  circular  mils, 
or  "  the  square  "  of  its  diameter,  therefore, 

-p    rn  M    —  R»   an(l>  assuming  the  length   to   be 

1500  feet  and  the  circular  mils  =  10.381,  the  resist- 

1500  X  10.79 
ance     would     equal        -.  Q  OQI —  1.559  ohms. 

The  cross-section  of  a  copper  wire,  in  circular 
mils,  is  found  by  multiplying  the  resistance  of  a 
foot-mil  (10.79)  by  its  length  (L)  in  feet,  and  divid- 
ing the  result  by  its  resistance  (R)  in  ohms  ;  there- 
fore, 

10.79  X  L 

-^ —  -  =  d8  or  c.  m.,  and,  the  resistance,  and 

length  of  the  wire  being  the  same  as  in  last 
example,  the  cross-section  in  circular  mils  would 

.  10.79  X  1500 
equal  =  10381  ==  c.  m. 


132  HOW    TO    WIRE   BUILDINGS. 

91.  Having  ascertained  the  resistance  of  the  con- 
ductors, at  the  desired  percentage  of  loss,  for  any 
given  number  of  lamps,  the  cross-sections  of  same 
can  be  found,  as  shown  in  the  previous  example. 
To  demonstrate:  assuming  35  lamps,  the  R  of  one 
=  90  ohms,  located  at  a  distance  of  1 60  feet  from 
the  dynamo,    and  5  per  cent,    being  the  loss   of 
energy  desired  in  the  conductors, 

90  ohms  R  of  lamps 

35  lamps  :  2'43  ohms  = :  Total  R  of 

lamps.     2.43  ohms  =  95  percent,  of  total  resistance 
of  circuit,  therefore  the  total  resistance  of  circuit 

2  43  X  100 

equals,  ^  -  =  2.558  ohms  =  Total  R  of  cir- 
cuit, and,  2.43  ohms  =  Total  R  of  lamps, 
therefore,  .  128  ohms  —  R  of  conductors. 
,The  distance  being  160  feet,  the  total  length  of  the 
wire  equals  320  feet,  and  the  cross-section  in  cir- 
cular mils,  of  a  wire  that  length  and  resistance,  is, 

10.79    x   320 

-jgg—   -  =  26.967  c.  m.  =  No.  6  B.  &  S.  gauge 

wire. 

92.  The  term  "difference  of  potential"   denotes 
that  portion  of  the  electromotive  force  which  exists, 
at,  or  between,   any  two  points  in  a  circuit,  and 
equals  the  electromotive  force,  (in  a  dynamo)  at 
the  point  where  the  armature  ' '  cuts  ' '  the  lines  of 


HOW   TO   WIRE   BUILDINGS. 


133 


force,  minus  the  amount  lost  in 
transmission,  due  to  the  resistance 
of  the  conductor  :  To  illustrate  :  In 
an  armature,  there  is  created  or 
generated  a  certain  amount  of 
current  at  a  certain  pressure  ;  the 
pressure  decreases  according  to  the 
resistance  of  the  conductors  ;  there- 
fore, the  electrical  pressure  at  the 
brushes  is  less,  due  to  the  resistance 
of  the  armature  coils,  than  in  the 
armature,  and  less  in  the  feeders, 
than  at  the  brushes,  etc. 

In  the  diagram  A  represents  an 
armature  of  a  dynamo,  B  represents 
the  commutator  or  brushes,  C  rep- 
resents the  feeder,  D  represents  the 
main,  and  E  represents  the  terminals 
at  the  lamp.  At,  or  in  A  is  "the 
electromotive  force  ;  that  is,  the  point 
at  which  the  electrical  pressure  is  the 
greatest.  The  pressure  at  B  is  less 
than  that  at  A,  due  to  the  resistance 
of  the  armature  coils,  consequently 
its  potency  is  less ;  that  is,  there 
is  at  this  point  a  "  difference  of 
potential,"  which  is  governed  by  the 


134  HOW   TO   WIRE   BUILDINGS. 

% 

resistances  of  the  conductors,  and  the  pressure 
at  B  plus  the  amount  lost  in  the  armature  coils, 
equals  "the  electromotive  force."  The  difference 
of  potential  in  C  the  feeder,  D  the  mains,  and  E  at 
the  lamp  terminals  is  governed  according  to  the 
same  conditions.  Assuming  the  electromotive  force 
in  A  equals  125  volts,  and  the  loss  or  drop  of 
electrical  pressure  in  the  armature  equals  1  per 
cent. ,  the  ' '  potential  difference ' '  at  the  brushes  B 
would  equal  123f  volts,  and,  if  the  loss  in  the  feeder 
€  equals  5  per  cent,  of  that  in  B,  the  difference  of 
potential  in  C  would  equal  117£  volts  ;  and,  if  in 
the  main  wire  D,  the  loss  is  equal  to  3  per  cent,  of 
the  pressure  in  C,  the  difference  of  potential  in  same 
would  equal  114  volts  ;  and,  if  the  loss  in  the  lamp 
wires,  is  equal  to  2  per  cent,  of  the  pressure  in  B, 
the  difference  of  potential  at  the  lamp  terminals 
would  equal  lllf  volts. 

93.  The  term  "  electromotive  force,"  is  generally 
used  to  denote  the  pressure  at  the  highest  pressure 
point ;  in  all  other  parts  of  the  circuit,  the  pressure 
is  noted  as  the  potential  difference,  or  difference  of 
potential. 


HOW   TO   WIRE   BUILDINGS.  135 


CHAPTER  XXI. 


RULES  FOR  ASCERTAINING  REQUIRED  SIZES  OF  WIRE. 

94.  The  following  rules  enable  us.  to  determine 
the  size  of  wire  necessary,  for  any  number  of  lamps, 
at  any  distance  (see  safe-carrying  capacity),  and  at 
any  desired  loss,  expressed  in  circular  mils  : 

RULE  1.  Multiply  the  resistance  of  one  foot-mil 
by  twice  the  distance,  and  by  the  number  of  lamps, 
and  by  100,  minus  the  per  cent,  loss,  and  divide 
the  result  by  the  resistance  of  one  lamp  multiplied 
by  the  percentage  of  loss.  The  loss  should  be 
expressed  as  a  whole  number.  Thus, 
Rof  1  Ft.  -mil  x  2  x  D  X  No.  of  lamps  100  —  loss 

R  of  one  lamp  %  loss 

—  C.  mils. 

Example  :  80  lamps,  located  at  a  distance  of  140 
feet,  R  of  Lamp  =  200  ohms,  to  determine  the  size 
of  wire  at  5  per  cent,  loss  : 
Foot-mil  =  10.79  ohms. 
10.70  X  2  X  140  X    80       100—5 

200  5 

241696       95        22961120 

x  5-=  -  =  22961  cir-  mlls  = 


B.  &  S.  G.  wire. 


136  HOW    TO    WIRE   BUILDINGS. 

RULE  2.  To  determine  the  size  of  wire,  the  loss 
or  '  '  drop  '  '  expressed  in  volts,  multiply  the  resist- 
ance of  one  foot-mil,  by  twice  the  distance,  and  by 
the  number  of  amperes,  and  divide  the  result  by 
the  number  of  volts  to  be  u  lost,"  thus, 
R  of  1  Ft.  -mil  x  2  x  D  x  amperes 
"Tolts  drop. 

Example  :     185  100-  volt  lamps,  located  at  a  dis- 
tance of  260  feet. 

The  resistance  of  each  lamp  =  140  ohms.     Drop 
=  3  volts. 

It  is  necessary  to  find  the  amount  of  current,  in 
amperes,  required  for  each  lamp,  and  according  to 

T^ 
Ohm's  law,  C  =  -g-  therefore,  the  current  required 

for,  or  consumed  by  each  lamp  equals, 
Volts  100        5 


-^-  x  185  =  132.14  amperes,  and, 

10.79  x  2  X  260  x  132.14 

—  —  -  =  247123  c.  mils. 


95.  Where  the  conditions  of  the   lamps  do  not 
change,  that  is,  where  the  wiring  is  installed  for. 
connection,  and  use   of  the  same  kind  of  lamps, 
continuously,  it  will  be  found  handy  to  have  '  '  a 
constant  "  already  calculated  for  the  different  losses, 


HOW    TO    WIRE    BUILDINGS.  137 

and  it  is  found  by  multiplying  the  resistance  of  one 
foot-mil,  by  two,  and  the  result,  by  100  minus  the 
desired  loss,  and  divide  the  result  by  the  resistance 
of  one  lamp  multiplied  by  the  loss.  The  loss  to  be 
expressed  in  whole  numbers,  thus, 
Rof  Ft.  -mil  x  2  100  —loss 


B  of  lamp 

assuming  the  R  of  lamp  =  200  ohms  and  the  loss 
=  5  percent.,  the  constant  would  be, 
10.79    x    2        100  —  5 


x 


200  5 

21.58        95         2050 

X  --  —    -  =  constant  2.05   =  and,   to 


ascertain  the  size  of  wire,  expressed  in  circular  mils, 
for  a  given  number  of  lamps,  a  certain  distance,  at 
any  desired  loss,  multiply  the  number  of  lamps,  by 
the  distance  in  feet,  and  the  result,  by  the  constant 
for  the  loss  desired  ;  thus, 

No.  lamps  X  distance  x  constant  =  cir.  mils. 
Example  :  The  resistance  of  lamp,  and  per  cent. 
loss,  as  in  previous  example  ;  determine  the  size  of 
wire  required,  for  175  lamps,  at  a  distance  of  135 
feet.  175  X  135  X  2.05  =  cir.  mils  =  48431  =  No. 
3  B.  &  S.  G.  wire. 

96.  The  cross-section  of  wire  should  be  such, 
that  it  will  conduct  the  current  without  becoming 
heated  to  the  point  where  the  temperature  is  greatly 


138  HOW   TO   WIKE   BUILDINGS. 

in  excess  of  that  of  the  surrounding  air.  The 
evidence  of  this  condition  can  be  got  by  grasping 
the  wire  with  the  bare  hand.  All  wires  become 
heated  when  a  current  of  electricity  is  passed 
through  them  ;  and  by  increasing  the  amount,  in 
amperes,  in  any  given  wire,  the  heat  is  increased. 

According  to  the  rules  for  wiring,  the  result  is 
the  same  in  circular  mils,  for  100  lights  one  foot  as 
for  one  light  100  feet.  It  is  easily  understood  that 
this  is  not  correct,  therefore  care- must  be  taken,  in 
short  distances  to  provide  a  sufficiently  large  wire, 
in  diameter,  so  that  same  will  not  become  unduly 
heated.  The  accompanying  table  is  a  safe  practical 
guide,  and  when  figuring  wire,  should  the  circular 
mils,  per  ampere,  be  less  than  mentioned  in  the 
table,  it  is  advisable  to  determine  the  sizes  required 
allowing  per  ampere,  the  number  as  stated  therein, 
rather  than  by  the  rules.  Allowance  in  circular 
mils  per  ampere,  being  the  safe  carrying  capacity. 


HOW    TO    WIRE    BUILDINGS. 


139 


SAFE  CARRYING  CAPACITY. 


AMPERE. 

ClR.  MILS 
PER 

AMPERE. 

WIRE 
B.  W.  G. 

WIRE 
B.  S.  G. 

I 

225 

16 

14 

5 

370 

16 

14 

10 

480 

14 

12 

15 

540 

12 

10 

20 

590 

12 

8 

25 

640 

10 

8 

30 

670 

8 

7 

35 

710 

8 

6 

40 

740 

7 

5 

45 

770 

6 

4 

50 

800 

6 

4 

55 

825 

5 

3 

60 

845 

4 

3 

65 

870 

4 

2 

70 

890 

3 

2 

75 

915 

2 

1 

80 

940 

2 

1 

85 

960 

2 

1 

90 

970 

2 

0 

95 

990 

1 

0 

100 

1010 

0 

0 

110 

1040 

0 

00 

120 

1070 

00 

00 

130 

1090 

00 

000 

140 

1120 

000 

000 

150 

1150 

000 

0000 

175 

1210 

0000 

0000 

200 

1270 

225 

1320 

250 

1370 

275, 

1410 

300 

1450 

325 

1490 

140  HOW    TO    WIRE   BUILDINGS. 


CHAPTER  XXII. 


E  N  E  R  (I  Y  —  P  O  W  E  R  . 

97.  The  energy  which  is  developed  in  a  circuit, 
when  a  current  of  one  ampere  flows  through  a 
conductor  whose  resistance  is  one  ohm,  is  termed  a 
watt.  The  watt  is  the  electrical  unit  of  power, 

and   equals  horse-power,    or,    horse-power    = 


33,000  foot-lbs.,  that  is,  a  horse-power  equals  that 
power  which  will  raise  33,000  Ibs.  a  distance  of  one 

foot,  in  one  minute  of  time,  and  -  H.  P.  =  44.25 

foot-lbs.  per  minute.  The  number  of  watts  developed 
in  a  circuit  is  determined  by  multiplying  the  am- 
peres by  the  volts, 

Amperes  X  volts,  or  C  X  E  =  watts,  or  C2  x  R 
=  watts. 

And  if  expressed  in  the  terms  of-  the  mechanical 
unit  (horse-power) 

CE       C2  R 

746~  or  ~74g~    =  horse-power. 

If  expressed  in  foot-pounds,  C  x  IJ  x  44.25,  or, 
C'  X  R  X  44.25  =  foot-lbs. 


HOW   TO   WIRE   BUILDINGS.  141 

Example :  Determine  the  electrical  energy,  ex- 
pressed in  horse-power,  developed  in  a  dynamo, 
connected  to  750 16-c.  p.  lamps,  each  lamp  requiring 
i  ampere  of  current  at  a  pressure  of  100  volts.  The 
loss  in  the  wires  equals  5  per  cent. 
750  lamps  X  i  -ampere  =  375  amperes, 

C  x  E  watts 

and,  375  amperes  x  100  volts  =  watts  =  37500  and, 
watts  x  44.25  =  foot-lbs. 

37500  x  44.25  =  1658375  =  the  energy,  expressed 
in  foot-lbs.,  expended  in  the  lamps,  and  represents 
95  per  cent,  of  the  total  as  the  remaining  5  per  cent, 
is  expended  or  lost  in  the  conductors,  therefore 
1658375  =  95  per  cent,  of  total  energy,  and 

87284  =    5    "      "  " 

1745659  —  Total  energy,  expressed  in  foot-lbs., 
expended  in  the  lamps  and  conductors,  and  foot- 
pounds, divided  by  33000  equals  horse-power,  there- 
fore, 1745659  •*-  33000  =  53  h,orse-power. 

To  find  the  actual  horse-power  expended  at  the 
pulley  of  the  dynamo,  assuming  the  efficiency  of 
the  dynamo  to  be  at  90  per  cent.,  and  according  to 
the  last  example,  1745659  foot-pounds  were  ex- 
pended in  the  lamps  and  conductors,  therefore,  the 
efficiency  of  the  dynamo  being  90  per  cent.,  it 
represents  only  90  per  cent,  of  the  power  expended 


142  HOW   TO   WIRE   BUILDINGS. 

at  the  pulley  of  dynamo,  and  as  1745659  =  90  %, 
and,  193962  =  10  % 

1939621  =  Total 

energy  in  foot-pounds  ;  therefore,  1939621  -*-  33000 
=  58.777  =  total  amount  of  energy  in  horse-power 
expended  at  the  pulley  of  the  dynamo,  and  if 
belted  to  engine,  10  per  cent,  being  lost  in  the 
transmission  of  power,  then 

58. 777  h.  p.  =  90%,  and 
6.53    h.  p.  =  10%  loss 
65.307  h.  p.  represents  the  amount  of 
horse-power  at  the  pulley  of  the  engine. 

In  the  first  example  it  was  shown  that  87.284  foot 
pounds  were  expended  in  the  conductors  due  to 
their  resistance,  which  equals,  87284  -*•  33000  = 
2.645  or  2|  horse-power,  and  the  cost,  in  dollars  and 
cents,  equals  2|  X  Ibs.  of  coal  per  h.  p.  hour  x 
cost  of  Ibs.  of  coal 

=  $  and  cts. 

This  is  but  another  example,  of  the  importance 
of  carefully  considering  the  question  of 
conductors. 


HOW   TO    WIKE   BUILDINGS.  143 


CHAPTER   XXIII. 


DYNAMOS  AND  MOTORS. 

,  98.  In  setting,  connecting,  or  running  a  dynamo, 
or  motor,  unless  you  are  familiar  with  all  its  parts, 
method  of  winding,  and  connections,  it  is  very 
important  that  a  blue  print  or  diagram,  showing 
the  different  parts,  and  method  of  connections,  etc., 
be  procured. 

99.  The  machine  should  be  located  in  a  clean,  dry 
place,  and  where  the  temperature  is  not  high  ;  it 
should  be  isolated,  as  much  as  pqssible,  from 
other  machinery,  especially  in  saw  mills,  machine 
shops,  etc.,  where  more  or  less  dust,  or  metal  filings 
are  flying,  but  at  the  same  time  it  should  be  access- 
ible. If  the  machine  is  set  on  an  ordinary  floor, 
provision  should  be  made  against  vibration.  The 
base  frame  should  be  treated  to  a  coating  of  hot 
parafnne,  for  closing  the  pores,  and  a  thick  coating 
of  shellac.  In  putting  the  machine  together,  care- 
must  be  taken  to  have  all  the  parts  clean,  and  all 
connections,  bearings,  etc.,  must  be  put  together  so 
that  the  "  fit "  will  be  perfect.  All  parts,  especially 
the  armature  and  magnets,  must  be  handled  with 


144  HOW   TO    WIRE   BUILDINGS. 

the  utmost  care,  and  must  not  be  handled  any  more 
than  is  necessary. 

100.  Before  starting,  adjust  and  test  the  brushes 
Jor  tension.     See  that  the  main  connections  in  the 
circuit  are  open  ;   examine  all  connections  ;  provide 
each  cup  or  automatic  lubricator,  with  sufficient  oil, 
and  see  that  the  feed  is  in  proper  working  order. 

In  a  shunt- wound  machine,  when  up  to  speed, 
the  brushes  can  be  dropped  on  the  commutator,  and 
if  hand  regulator  is  used,  the  resistance  should  be 
thrown  out  of  the  fieldv  until  the  needle  on  the 
indicator  is  at  the  point  showing  the  required 
pressure.  The  lamp  at  the  head  of  the  dynamo  is 
generally  a  guide. 

101.  It  is  preferable  to  ran  the  machine,  for  an 
hour  or  so,  at  full  speed,  without  any  current  gen- 
erated, so  that  the  bearings  can  be  worked  smooth, 
and  tested   before  the  machine   is   put  to   actual 
work,  and  in  case  the  bearings  become  heated,  the 
defect  must  be  remedied. 

When  a  shunt- wound  machine  is  to  be  connected 
in  circuit,  in  multiple  with  another,  it  should  be 
brought  up  to  speed,  and  the  field  resistance  grad- 
ually thrown  out,  until  the  pilot  lamp,  at  the  head 
of  the  machine,  is  practically  at  its  full  normal 
candle-power.  The  machine  can  then  be  connected 
in  the  circuit,  and  by  watching  the  pressure  indi- 


HOW   TO   WIRE   BUILDINGS.  145 

cator,  and  throwing  out  the  field  resistance,  the 
machine  will  gradually  perform  its  share  of  the 
work.  When  two  or  .more  shunt- wound  machines 
are  in  multiple,  all  field  and  line  connections  should 
be  traced  and  examined  before  starting. 

102.  In  a  compound-wound  machine,  the  magnets 
are  wound  similarly  to  those  of  the  ordinary  shunt- 
wound  machines,  but  have,  in  addition,  extra  coils 
in  series,  and  arranged  so  that  according  to  the 
number  of  lamps  in  use,  each  receives  a  certain 
amount  of  the  current.  A  change  in  the  number  of 
lamps,  connected  in  the  circuit,  will  cause  an 
increase  of  current  in  one,  and  a  proportionate 
decrease  in  the  other,  so  that  the  pressure  is  kept 
at  a  constant  point,  the  series  coils  acting  as  an 
automatic  regulator. 

Any  number  of  machines  can  be  run  in  multiple, 
provided  the  pressure  or  electromotive  force  of 
all  corresponds.  Should  the  pressure  on  one 
be  less  than  that  of  the  others,  it  is  liable  to 
be  run  by  them  as  a  motor.  With  dynamos 
connected  in  multiple,  the  pressure  of  all  is  equal 
to  that  of  any  one  machine,  but  the  current,  in 
amperes,  is  increased  according  to  the  capacity 
of  all,  for  example  :  Three  machines  having  a 
capacity  of  100,  50  and  25  amperes,  respectively, 
the  pressure  of  each  equals  125  volts,  the  com- 


146  HOW    TO    WIRE    BUILDINGS. 

bined    output    would    equal    175    amperes    at    a 
pressure  of  125  volts. 

103.  In  stopping  the  machine,  if  running  singly, 
slow  the  speed  of  the  engine,  which  reduces  the 
pressure  in  the  dynamo  ;  throw  the  resistance  coils 
in  the  field  circuit,  if  hand  regulator  is  used  ;  and 
just  before  the  engine  is  stopped,  break  the  line 
connection,  and  lift  the  brushes. 

If  the  machine  is  connected  in  multiple  with 
another,  in  order  to  stop  or  disconnect  it  from  the 
circuit,  regulate  its  amount  of  work  so  that  it  will 
be  as  small  as  possible,  then  break  the  line  connec- 
tion ;  but  the  field  must  correspond  in  strength  to 
that  in  the  other  machines,  so  that  it  may  not  be 
run  as  a  motor. 

This  same  method  applies  to  machines  connected 
to  three-wire  circuits,  and  also  to  compound- wound 
machines,  when  the  equalizer  is  kept  closed. 

104.  Two  dynamos  connected  to  the  three-wire 
system,    are  practically   similar    to   two   dynamos 
connected  in  multiple  ;  the  positive  of  one,  and  the 
negative  of  the  other  machine,  are  connected  to  the 
middle  or  neutral  wire  of  the  circuit.     The  other 
pole  of  each  machine  forms  the  positive  and  nega- 
tive pole,  respectively. 

In  starting  the  machines,  each  should  be  started 
separately,  and  not  at  the  same  time.  When  one 


HOW    TO    WIRE   BUILDINGS.  147 

machine  is  connected  and  running,  the  second 
machine,  when  up  to  the  required  pressure,  can  be 
connected  in  the  circuit.  The  method  of  stopping, 
as  stated,  is  the  same  as  if  in  ordinary  multiple. 

105.  In  connecting  machines  in  series,  the  positive 
pole  of  one  connects  with  the  negative  pole  of  the 
next  machine  ;  the  current  in  amperes  remains  con- 
stant, but  the  pressure  in  volts  increases  with  every 
additional  machine  ;  the  voltage  of  the  machines 
need  not  be  the  same,  but  the  current  capacity  of 
each  must  correspond  with  the  others. 

In  constant  current  machines,  when  starting,  it 
is  only  necessary  to  examine  the  connections,  and 
have  the  circuit  completed.  The  line  or  circuit 
should  never  be  broken  while  running,  as  the  field 
may  "burn  out,"  or  if  broken  at  the  brushes,  an 
arc  will  be  created,  that  will  burn  the  commutator. 
In  stopping  simply  slow  the  speed,  if  possible, 
until  the  armature  stops  revolving. 

If  connected  to  shafting,  or  arranged  so  that 
speed  cannot  be  stopped,  then  open  the  field  circuit, 
but  under  no  consideration,  must  the  line  be  broken. 

The  method  of  starting  and  stopping  is  the 
same  for  a  single  series  machine,  or  a  number  of 
them. 

106.  In  setting  up   motors,   the  same   care  and 
attention  must  be  given  to  all  the  parts  and  bear- 


148  HOW   TO    WIEE   BUILDINGS. 

ing,  as  to  dynamos.  A  blue  print  or  diagram, 
showing  the  method  of  connecting  the  motor  and 
the  starting  or  regulating  box,  and  directions  for 
running  same,  should  be  provided. 

In  a  series-wound  motor,  which  is  connected  in 
an  "arc  light"  circuit,  the  connections  are  simple. 
The  motor  is  "  cut-in"  the  circuit  in  the  same 
manner  as  an  arc  lamp,  a  switch  is  provided  and 
connected  in  the  line  (arc  light  hand  switch),  which 
is  used  for  starting  or  stopping  the  motor  ;  as  in  a 
series  dynamo,  the  line  must  never  be  broken,  or, 
the  brushes  must  never  be  raised  from  the  commu- 
tator. 

Constant  potential  motors  are  wound  in  a  manner 
similar  to  the  ordinary  shunt- wound  dynamo,  and 
with  each  motor  is  provided  a  starting  box,  com- 
posed of  a  number  of  coils,  and  constructed 

« 

somewhat  similar  to  a  resistance  box,  used  for 
regulating  the  field  of  shunt- wound  dynamos.  The 
wire  forming  one  side  of  the  circuit  is  connected  to 
the  post  of  the  cross-bar,  on  the  face-board  of  the 
starting  box,  and  the  cross-bar  through  a  coil  in 
the  box  forms  the  connection  between  one  of  the 
field  wires  and  the  line.  The  cross-bar  also  forms, 
through  a  number  of  coils,  the  connection  between 
the  line  and  one  of  the  brush  wires.  The  line 
should  always  be  provided  with  a  double-pole  cut- 


HOW    TO    WIRp:    BUILDINGS.  1491 

out  and  switch.  To  start  the  motor,  close  the 
switch  in  the  line,  and  turn  the  connecting  strip  or 
cross-bar  on  the  starting  box,  until  it  rests  on  the 
first  connecting  plate  on  each  side.  Allow  it  to 
rest  on  these  for  an  instant,  so  that  the  fields  will 
be  charged.  As  the  armature  begins  to  turn,  move 
the  cross-bar  from  plate  to  plate,  which  throws  out 
the  resistance,  and  the  motor  will  then  have  attained 
its  full  speed.  The  movable  bar  on  the  starting 
box  must  not  be  allowed  to  rest  on  any  of  the  con- 
necting plates  (with  the  exception  of  the  first,  for 
only  a  moment),  but  must  be  steadily  moved  to  the 
last  plate.  This  box  is  not  to  be  used  as  a  regu- 
lator, but  is  only  for  use  when  starting  or  stopping, 
as  the  capacity  of  the  wires  is  not  sufficient  to  carry 
the  current  for  even  a  short  space  of  time. 

107.  A  speed  regulator  is  constructed  in  a  some- 
what similar  manner  to  the  starting  box,  and  the 
cross-section  of  the  wires  is  such,  that  they  can 
carry  the  current  without  unduly  heating.  In 
stopping,  turn  the  handle,  at  the  starting  box,  .in 
the  opposite  direction  to  that  when  starting,  and 
when  it  is  brought  to  the  last  connection,  the  circuit 
is  broken,  although  it  is  more  preferable  to  allow 
the  bar  to  rest  on  the  connecting  plate,  next  to  the 
last,  and  break  the  connection  at  the  line  switch. 


150  HOW   TO   WIRE   BUILDINGS. 


CHAPTER    XXIY. 


PULLEYS. 

108.  In  all  machines,  whether  a  dynamo  or  motor, 
the  pulley  is  furnished  with  the  machine.  The 
width  of  face  and  diameter,  have  been  determined 
by  the  maker.  The  size  of  the  pulley  on  the 
dynamo  has  been  determined,  according  to  the 
speed  and  power  required  to  drive  it  when  at  its 
full  rated  capacity.  The  pulley  on  the  motor  is 
determined  by  the  rated  speed  at  which  the  motor 
is  to  run,  and  its  rated  horse-power. 

The  pulleys  on  the  machines  should  not  be  altered, 
or  pulleys  of  other  dimensions  used  ;  and  where 
conditions  exist,  which  necessitate  a  change  in  size, 
the  maker  should  be  notified.  He  will  either  make 
the  change,  or  forward  instructions  regarding  the 
matter. 

In  dynamos  driven  by  an  engine,  the  dimensions 
of  the  driving  wheel  is  usually  determined  by  the 
electric  lighting  company  or  the  maker  of  the 
engine.  The  diameter  is  determined  by  the  number 
of  revolutions  per  minute  of  the  engine  shaft,  the 
revolutions,  per  minute,  necessary  for  the  capacity 


HOW   TO   WIRE   BUILDINGS.  151 

of  the  dynamo,  and  the  diameter  of  the  dynamo 
pulley.  When  the  dynamo  is  belted  to  a  pulley  on 
a  countershaft,  the  shaft  must  be  considered  as  the 
shaft  on  the  engine. 

The  face  or  width  of  a  pulley  is  a  trifle  larger 
than  the  width  of  the  belt. 

109.  To  ascertain  the  required  diameter  of  the 
driving  pulley :  Multiply  the  diameter  of  the 
dynamo  pulley  by  the  number  of  revolutions  per 
minute  required,  and  divide  the  product,  by  the 
number  of  revolutions  per  minute,  of  the  shaft, 
Dia.  of  Dynamo  Pulley  x  required  speed  _ 

Revolutions  of  shaft,  per  minute, 
diameter  of  driving  pulley. 

Example  :  To  determine  the  diameter  of  pulley 
to  drive  a  dynamo,  having  a  pulley  10  inches  in 
diameter,  and  requiring  1,500  revolutions  per 
minute.  The  revolutions  of  the  shaft  per  minute 
=  225,  therefore, 

10  X  1500 
— — =  66|  inches  =  diameter  of  driving 

pulley. 

In  motors,  the  dimensions  of  the  pulley  being 
already  determined  by  the  maker,  the  speed  at 
which  the  machinery  or  shaft  is  driven  by  the 
motor,  depends  on  the  speed  of  the  motor,  and  the 
diameter  of  the  pulleys.  The  diameter  of  the 


152  HOW   TO    WIRE   BUILDINGS. 

pulley  on  the  machine  or  shaft  to  be  driven  at  a 
certain  speed,  depends  upon  the  speed  and  diameter 
of  the  motor  pulley. 

To  ascertain  the  diameter  of  the  driven  pulley  for 
any  desired  speed   or  number  of  revolutions  per 
minute,  multiply  the  revolutions  per  minute,  of  the 
motor  pulley,   by    its    diameter,    and  divide    the 
product,  by  the  number  of  revolutions,  desired  for 
the  driven  pulley.     Thus, 
Speed  of  motor  x  diameter  of  motor  pulley 
Desired  number  of  revolutions  for  driven  pulley 
Diameter,  in  inches,  of  driven  pulley. 

Example  :  To  determine  the  diameter  of  a  pulley 
requiring  200  revolutions  per  minute,  the  rated 
speed  of  the  motor  being  1,200  revolutions  per 
minute,  and  the  diameter  of  pulley  on  same  equals 
9  inches,  therefore, 

1200  X  9 

QQQ        =  54  inches  =  diameter  of  driven 

pulley. 

By  these  methods,  the  driving  or  driven  pulley 
can  be  ascertained, 


HOW   TO    WIKE   BUILDINGS.  153 


CHAPTER  XXV. 

BELTING. 

110.  All  belts  and  lacing  should  be  the  best  pro- 
curable.    The  belt  should  be  placed  on  the  pulley, 
with  the  smooth  side  in  contact.     If  the  belt  tends 
to  run   to   either  edge  of  the  pulley,   move    the 
dynamo  or  motor  in  that  direction,  until  the  belt 
remains  in  the  centre. 

Do  not  skimp  on  the  width  or  length  of  the  belt, 
it  being  desirable  to  have  it  a  trifle  larger  than  is 
actually  necessary  rather  than  too  small. 

In  dynamos  or  motors,  the  width  of  the  belt  is 
governed  by  the  width  of  the  face  of  the  pulley  on 
same.  The  pulley  is  usually  one  inch  wider  than 
the  belt. 

Belts  driven  horizontally  give  better  satisfaction 
than  those  driven  in  a  vertical  position,  as  the  arc 
of  contact  is  increased  in  horizontal  driving. 

111.  Avoid  excessive  strain,  and  protect  the  belts 
from  dirt,  exposure,  extreme  dampness  or  extreme 
dry  ness.     Applying  neats-foot  oil  occasionally  will 
keep  the  belt  soft  and  pliable. 


154  HOW   TO   WIRE   BUILDINGS. 

112.  A  single  belt  traveling  1,000  feet  per  minute 
transmits  one  horse-power,  provided  the  arc  of 
contact  equals  180°,  or  if  it  binds  or  touches  one- 
half  the  surface  of  the  circumference  of  the  pulley. 

Rule  for  ascertaining  the  width  of  belt  for  any 
desired  horse-power : 
Width  of  belt  x  speed  of  belt  in  ft.  x  arc  of  contact 

1000. 
=  h.p. 


HOW   TO   WIRE   BUILDINGS.  155 


CHAPTER  XXVI. 


ENGINES. 

113.  Although  wiremen  are  not  expected  to  be 
steam  engineers,  yet  there  are  times  when  a  knowl- 
edge of  starting  and  stopping  an  engine  may  be 
very  serviceable,  as  in  the  case  of  sudden  sickness 
of  the  engineer  in  charge  of  plant,  and  where  illum- 
ination is  imperatively  required. 

The  engines  mostly  used  for  driving  dynamos  are 
of  the  horizontal,  high-speed  type.  The  steam 
pressure  is  usually  80  pounds  to  the  square  inch, 
to  obtain  the  required  speed  of  revolution. 

114.  Before  starting  an  engine,  supply  all  the  oil 
cups  and  "  self  "  -lubricators  with  a  sufficient  amount 
of  oil,  and  see  that  the  "  feed  "  is  properly  adjusted. 
Open  the  rear  ports,  or  drips,  usually  located  in 
the  back  of  and  under  the  cylinder,  to  allow  any 
condensed  water  to  run  out.     Set  the  engine  on  its 
"centre"  and  then  slightly  open  the  steam  valve, 
to  heat  the  piston  and  cylinder.     When  one  side  is 
"  warmed  up"  turn  the  pulley  over  to  the  opposite 
"  centre"  and  heat  the  opposite  part  of  the  cylin- 
der, piston,  etc.     When  the  engine  is  heated,  and 


156  HOW   TO   WIRE   BUILDINGS. 

the  steam  gauge  indicates  the  pressure  required, 
open  fully  the  exhaust  valve,  close  the  rear  ports, 
or  drip  cocks,  and  slightly  open  the  steam  valve. 
Turn  the  driving  pulley  in  the  proper  direction, 
and  when  the  engine  is  running  slowly,  note  whether 
it  is  running  smoothly.  Keep  opening  the  steam 
valve  gradually,  until  it  is  fully  opened,  and  the 
engine  is  running  at  full  speed.  Attention  can  then 
be  given  to  the  starting  of  the  dynamo. 

115.  While  the  engine  is  running,  observe  from 
time  to  time  the  amount  of  pressure  indicated  at 
the  gauge,  and  watch  the  lubricators,  etc. 

If  any  loud  noise  or  pounding  be  heard  in  the 
engine,  shut  down  at  once,  as  water  may  from  some 
reason  have  been  carried  into  the  cylinder,  and  if 
the  engine  were  kept  running,  the  result  would  be 
that  the  cylinder-head  would  be  blown  out,  and  the 
engine  be  ruined. 

To  stop  the  engine,  gradually  close  the  steam 
valve,  be  careful  that  the  engine  is  not  stopped  too 
sudden.  Slowly  bring  the  driving  wheel  to  a  stand- 
still. When  the  engine  is  stopped,  close  the  feed 
of  the  lubricators,  clean  all  parts  of  the  engine,  and 
cover  it  with  the  cloth  provided  for  the  purpose. 

116.  Under  no  consideration  must  it  be  attempted 
to  repair  any  part  or  parts  of  the  engine,  and  it  is 


TO    WIRE   BUILDINGS.  157 

suggested  that,  unless  the  engine  is  in  good  order, 
and  the  case  urgent,  the  wireman  should  not  in  any 
manner  handle  the  engine,  unless  he  is  an  expe- 
rienced engineer. 


158  HOW   TO   WIRE   BUILDINGS. 


CHAPTER  XXVII. 

CONCLUSION. 

117.  Wiremen  should  familiarize  themselves  with 
the  different  kinds  and  qualities  of  material,  so  that 
they  may  be  enabled  to  get  the  best  of  any  partic- 
ular kind.  In  the  matter  of  appliances,  they  should 
know  just  what  is  the  best  for  the  special  purpose. 
New  appliances,  etc.,  are  being  placed  on  the 
market  continually,  and  unless  a  knowledge  of  the 
same  is  acquired,  antiquated,  obsolete  and  inferior 
materials  and  devices  will  be  used  to  the  disad- 
vantage of  the  customer.  The  writer  would  advise 
all  wiremen  to  subscribe  to  some*  journal  devoted 
exclusively  to  the  discussion  and  publication  of 
electrical  engineering  work.  Hardly  a  week  goes 
by  but  what  some  one  or  more  articles  treat  on  new 
methods  of  wiring  and  kindred  work.  It  is  very 
instructive  and  at  the  same  time  interesting.  We 
are  also  enabled,  through  the  same  source  to  obtain 
information  on  the  various  appliances,  and  where 
the  same  can  be  purchased.  We  are  better  able  to 
keep  in  line  with  all  improvements  in  all  branches  ; 
as  an  instructor,  the  press  has  no  equal,  and  it  has 


HOW   TO   WIRE   UUILDINGS.  159 

the  advantage,  moreover,  of  continually  devising 
new  ways  by  which,  the  wireman  may  get  greater 
profit  from  his  experience  and  rise  to  larger 
responsibilities  and  opportunities. 


160 


HOW    TO    WIRE    IUTILDINGS. 


TABLES  OF  DIFFERENT  GAUGES,  WITH  THEIR  RESPECTIVE 
DIAMETERS  AND  AREAS. 


BROWNE  &  SHAKPK. 

BIRMINGHAM. 

No.  of 
Gauge. 

Diameter 
in  Mils. 

Area  in 

C  M  =  d2. 

No.  of 
Gauge. 

Diameter 
in  Mils. 

Area  in 
CM  =  da. 

4-0 

.4600 

211600 

4-0 

.454 

206116 

3-0 

.425 

180625 

3-0 

.4096 

167805 

2-0 

.3648 

133079 

2-0 

.380 

144400 

0 

.340 

115600 

0 

.3249 

105592 

1 

.300 

90000 

1 

.2893 

83694 

2 

.284 

80656 

2~ 

.2576 

66373 

3 

.259 

67081 

3 

.2294 

52634 

4 

.238 

56644 

5 

.220 

48400 

4 

.2043 

41742 

6 

.203 

41209 

5 

.1819 

33102 

7 

.180 

32400 

6 

.162 

26244 

8 

.165 

57225 

7 

.1443 

20822 

9 

.148 

21904 

8 

.1285 

16512 

10 

.134 

17956 

9 

.1184 

13110 

11 

.120 

14400 

10 

.1019 

10381 

12 

.109 

11881 

11 

.0907 

8226 

13 

.095 

9025 

12 

.0808 

6528 

14 

.083 

6889 

13 

.072 

5184 

15 

.072 

5184 

14 

.0641 

4110 

16 

.065 

4225 

15 

.0571 

3260 

17 

.058 

3364 

16 

.0508 

2581 

18 

.049 

2401 

17 

.0452 

2044 

19 

.042 

1764 

18 

.0403 

1624 

19 

.0359 

1253 

20 

.035 

1225 

20 

.032 

1024 

21 

.032 

1024 

21 

.0285 

820 

22 

.028 

784 

22 

.0253 

626 

23 

.025 

625 

23 

.0226 

510 

24 

.022 

484 

24 

.0201 

404 

25 

.020 

400 

25 

.0179 

320 

26 

.018 

324 

HOW   TO    WIRE    BUILDINGS. 


161 


WEIGHT    OF    COPPER   WIRE. 


No. 

ONE  THOUSAND  FEET. 

ONE  MILE. 

B.  AS. 

B.  W.  G. 

B.  &  S. 

B.  W.  G. 

0000 

039.33 

622.30 

3375 

3280 

000 

507.01 

540.22 

2077 

2884 

00 

402.09 

430.50 

2123 

2305 

0 

319.04 

349.03 

1084 

1840 

1 

252.88 

272.17 

1335 

1437 

2 

200.54 

243.70 

1058 

1287 

3 

159.03 

202.84 

.839 

1071 

4 

120.12 

171.21 

005 

904 

5 

100.01 

140.40 

528 

773 

6 

79.32 

124.43 

418 

057 

i 

02.90 

97.92 

332 

547 

8 

49.88 

82.39 

203 

435 

9 

39.50 

00.29 

209 

350 

10 

31.37 

54.30 

100 

287 

11 

24.88 

43.50 

131 

230 

12 

19.73 

35.98 

104 

190 

13 

15.05 

27.27 

83 

144 

14 

12.41 

20.83 

05 

110 

15 

9.84 

15.72 

52 

83 

10 

7.81 

12.88 

41 

08 

17 

0.19 

10.18 

33 

53f 

18 

4.92' 

7.20 

20 

38 

19 

3.93 

5.30 

20f 

28 

20 

3.09 

3.00 

16J 

19* 

21 

2.45 

3.09 

13 

l«i 

22 

1.94 

2.37 

10J 

12* 

23 

1.54 

1.94 

4 

10J 

24 

1.22 

1.47 

6* 

7} 

25 

.97 

1.22 

54 

6* 

20 

.77 

.95 

4 

5 

27 

.01 

.75 

H 

4 

28 

.48 

.Gl£ 

2* 

si 

29 

.38 

.50 

2 

20 

30 

.30 

.42 

if 

H 

162  HOW    TO    WIKE   BUILDINGS. 


TABLE  SHOWING  FRACTIONS  OF  AN  INCH  REDUCED  TO 
DECIMAL  EQUIVALENTS. 


^y equals   .015625 

^ "  .031250 

-fo "  .046875 

fa "  .062500 

-g-5¥ "  .078125 

-fz "  .093750 

^ "  .109375 

% "  .125000 

/T "  .140625 

3\ "  .156250 

U "  .171875 

fa «  .187500 

|J "  .203125 

-^ "  .218750 

|J "  .234375 

J- "  .250000 

|J "  .265625 

^ "  .281250 

if "  .296875 

-fa "  .312500 

fj-  "  .328125 

1^ "  .343750 

|| "  .359375 

I "  .375000 

ff "  .390625 

t| «  .406250 

|i "  .421875 

TTL »  .437500 

II "  .453125 

if "  .468750 

|J "  .484375 

£ "  .500000 


INDIA  RUBBER      

AND  QUTTA=PERCHA 

INSULATING  COMPANY, 


W.  M.  HABIRSHAW,  General  Manager, 
315   MADISON   AVENUE, 

NEW  YORK   CITY.  U.  s   A. 


„ 

3        HABIRSHAW 

*'**» 


"THE    NATION'S    CHOICE.1 


GBIMSHAW 
White  Core  Wires. 

GRIMSHAW  TAPES. 
VULCA  ELECTRICAL  WIRE  DUCTS. 

RAVEN  CORE  WIRES. 
COMPETITION  LINE  WIRES. 


SOLE    MANUFACTURERS, 


New  York  Insulated  Wire  Co., 

15  Cortlandt  St.,  New  York. 

BRANCHES :— Boston,  Chicago,  Sail  Francisco. 

Foster   on  Central  Station  Management 
and   Finance. 


PROFUSELY  ILLUSTRATED   WITH  SPECIAL  FORMS,   Etc. 


This  is  what  President  Huntley,  of  the  National  Electric  Light  Association, 
said  regarding  it  in  his  inaugural  speech  : 

"A  most  valuable  series  of  articles  on  Central  Station  Management  and 
Finance,  by  H.  A.  FOSTER.  I  trust  every  Electric  Light  Man  will  read  it. 
The  subject  is  admirably  treated  from  a  practical  standpoint,  and  it  is  impos- 
sible not  to  derive  good  from  the  many  hints  and  suggestions,  while  the  many 
forms  and  blanks  may  be  adopted  with  much  benefit.11 

This  strong  endorsement  is  seconded  by  many  other  authorities. 

The  perusal  of  this  pithy  book  and  the  use  of  its  "pointers"  will,  in  truth, 
save  any  company  thousands  of  dollars. 


CLOTH,    $1.5O,    POST-PAID. 

C.  C.  SHELLEY, 


10  &  12  College  Place,  New  York, 


THE  INTERIOR  CONDUIT  SYSTEM. 


AS    IT    IS    APPLIED. 


THK  Standard  Method  of  Electric  Wiring, 


INTERIOR  CONDUIT  TUBING 
:   !  AND  APPLIANCES.   I   i 


MANUFACTURED     BY 


INTERIOR  CONDUIT  &  INSULATION  CO,, 

EDWD  H.  JOHNSON.  (      44    BROAD    STREET,      |         E.  w.  LITTLE, 

PRESIDENT.  /  NEW     YORK.  *         VICE-PRESIDENT. 


The  Safety  Insulated  Wire  &  Cable  Co. 

OFFICE:  234  W.  29th  STREET,  NEW  YORK, 

...     MANUFACTURERS    OF     ... 

SAFETY  UNDERGROUND  CABLES, 
REQUA  WHITE  CORE  INSULATION. 
SAFETY  SOLID  RUBBER  INSULATION, 
SAFETY  NAVAL  MARINE  INSULATION. 

ALL  MADE   WITH  A  VIEW  TO 

PERFECT   SAFETY  FOR  ELECTRIC  LIGHTING. 

Insulated  Wires  and  Cables  for  Electric  Power,  Telegraph, 
Telephone,  Submarine  and  Inside  Purposes. 

The  White  Core  and  Solid  Rubber  is  covered  with  an  abso- 
lutely Fireproof  Braid,  which  has  been  approved  by  the  Under- 
writers of  New  York,  Boston,  Baltimore  and  other  large  cities ; 
and  has  been  used  in  the  new  main  offices  of  the  Western  Union, 
Mail  and  Express,  and  Postal  Buildings ;  Madison  Square 
Garden ;  Hotels  Savoy,  Waldorf,  Holland  and  Netherlands ; 
Presbyterian  Hospital,  and  many  more  of  our  largest  buildings. 

FIVE  MILLION  FEET  OF  SAFETY  CONDUCTORS 
:     :     ;     USED  AT  THE  WORLD'S  FAIR.     ;     ;     : 

OUR  SAFETY  NAVAL  CORE  has  been  used  in  the  in- 
stallation of  the  following  new  war  vessels  : — NEW  YORK, 
CINCINNATI,  TEXAS,  RALEIGH,  BANCROFT,  MARBLE- 
HEAD,  COLUMBIA,  MIANTONOMOH,  OLYMPIA  and 
OREGON. 

OVER  FIVE  HUNDRED  MILES  OF  SAFETY  UNDER- 
GROUND CABLES  now  in  use  in  the  New  York  subways. 

ARCHITECTS,  PLEASE   NOTE 
AND    SEND    FOR    SAMPLES. 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 
BERKELEY 

Return  to  desk  from  which  borrowed. 
This  book  is  DUE  on  the  last  date  stamped  below. 


L 

JUN  27  19 


LD  21-100m-9,'47(A5702sl6)476 


865697 


THE  UNIVERSITY  OF  CALIFORNIA  LIBRARY 


